The beginnings of Lech's history are linked to an organization that wasn't directly connected to the sport - Catholic Youth Society. In 1920 the youth finally decided to abandon the relatively passive society and form its own football team. The registration of the club took place on a Sunday, on March 19th, 1922. Therefore, that is the date considered as the official birthday of Lech.

Jan Dyzman, a treasurer who sang in a choir during his free time, suggested that the club was named Lutnia (the choir he was a member of was called the same, too). The idea was approved by his teammates, however on September 4th the club was renamed to Sport Association Dębiec League. The name was significant since most of the youth that played at the club inhabited Dębiec district.

Jan Nowak was the first chairman, but he occupied the seat for a few months only, having been called by the army. On September 4th when the final decision about the new name of the club had to be taken, Antoni Stachowski became the chairman.

On June 29th, 1924 the team debuted in the league and won with Ruch Poznań 5:3. The result was later verified and changed to a 3:0 win since the rival's squad did not fully obey the rules of the game.

Similarly to many other clubs, Sport Association Dębiec League had problems with the payment of obligatory dues and has been suspended for a specific period of time. In January 1925 Dębiec district became an official part of Poznań city and the club changed its name to Sport Association Poznań League.

During this period of time the fight for power took place. In 1925 Leon Nowicki became the chairman of the club, just to be replaced by Stanisław Dereziński a few months later. In the mean time, the club strengthened and soon was considered one of the best in its region. 

In 1927 Sport Association Poznań League won 17 out of 22 matches (and drew three of them). On April 10th 1927 the club beat Helios Czempin 9:0. Łucjan Kunz scored 7 goals in that game. It was the best results achieved by an individual player in the history of the club, until Włodzimierz Jakubowski came along and produced a similar score. That same season the club was promoted to B-class.

In the mean time a reserve team was created, which only empowered the rivalry. The players at the club fought of the games as an opportunity to promote themselves and be noticed by another team at which they could earn a living. At Sport Association Poznań League wages were only Dereziński's distant plans. 

In 1928 the B-class league was relatively solid, with 5 qualification groups. At that point Sport Association Poznań League performed really well, losing to the winners of the group only (1928, 1929), which placed them second.

The club still lacked official colors and a crest. At first the team wore red shirts sewed by Buchert company. The blue colors were adopted when the club was linked to the railway and moved to the stadium located at Dzierżyńskiego Street. However, that only took place about 30 years after the club's been formed.

Lech finally got promoted to the highest-ranked league in the region in 1932. Later the regulations were changed and the teams from A-class got a chance to qualify to the I national league. The players from Dębiec failed to join the top of the national football before the II World War began, but another historical event took place in the mean time. In Autumn 1933 KPW (Railway Army Training Organization) formed a sports club that shortly after the end of the war searched for a way to bring football back to life in Poznań. Lech was the first club that has been reactivated after the war!

Due to the war and the fact that many players were involved on the war fronts, the league was suspended. Nevertheless, the hunger for the football entertainment remained and in August 1940 an Organizational Committee of City Football Championships was created. Most of the footballers were forced to leave Poznań, and therefore couldn't compete, but those who stayed, played whenever could.

In 1940 the City Championships, by many considered unofficial, were won by Chwaliszewo, who turned out to be better than its three rivals - Strzelecka, Woźna and Wilda.

In 1941 9 teams participated in the competition and two seperate groups were formed. The tournament lasted 5 weeks and footballers from Górczyn and Dębiec KPW won their groups. On September 7th 1941 Dębiec and Strzelecka met in the final, but gendarme stopped the match and it was never resumed.

A year later the championships did not take place and in 1943 they were aborted once again. On March 1945 the final from 1941 was repeated.

As the war approached an end, people began to think of a way to resume the league. On February 28th 1945 Leopold Krzyżanowski, once of the KPW members from before World War II, began working at the railway again. He received a permission to take over the stadium in the Dębiec region and even though it hasn't been clearly stated, KPW Poznań League was brought to life once again.

On March 16th 1945 Józef Chrobak was named as the new chairman of the Railway Sport Club. As the club rose back to its feet, new chairmen were chosen, mostly from the railway employment structures.

The club participated in the repetition of the City Championships from 1941. In the final Railway Sport Club beat Warta Poznań 1:0. The league was resumed in July 1945. In the first league clash after the war the future star Teodor Anioła debuted. Railway Sport Club faced Polonia Jarocin and won 11:1.

28 teams participated in the qualification to the top Polish league in 1948. The clubs were divided into three groups. The winner of each groups advanced to Ekstraklasa.  Before the first qualification match took place, the official 'fusion' of Railway Sport Club and Pogonia Sport Club was confirmed.

One of the conditions of the 'fusion' was a new name which contained the word Pogon. Nevertheless, the journalists remained using the name Railway Sport Club. A year later after the name was approved by the board, another change came and the club was renamed again. The word 'Pogoń' was dropped and the club which was founded in 1914 vanished from the map, never to be reborn.

The fight for the qualification to Ekstraklasa was exhilarating. Railway Sport Club was ranked fourth, but after a reexamination of the match against Polonia Bytom, the club moved a place up the rank. In January 1948 one of Polonia Świdnica players testified under the oath that two footballers in Polonia's squad played under a false name. Ekstraklasa now consisted of 14 teams, two more than before, and therefore Railway Sport Club qualified to the top league.

In the first Ekstraklasa match played on March 14th 1948, Railway Sport Club lost against Widzew 4:3. The team from Łódź had a great kick-off, but many losses followed and eventually they fell to the lower league.

The famous newspaper "Start" criticized the match of the two recently qualified clubs and undermined their competence to play in Ekstraklasa. Nevertheless, the club from Dębiec was ranked sixth, won the award "for the fairest playing team in 1948", while its three players, Czapczyk, Anioła and Białas gradually became stars. The famous ABC trio scored 40 goals in 1949 (Anioła - 20, Białas - 12, Czapczyk - 8). That same season the club was placed third in the league.

In 1960 Lech returned to the top Polish league, but in 1963 another degradation took place and this time the club needed 9 years to qualify again. In the mean time, Lech fell to the III league, also referred to as the League of the Voivodeships. Jerzy Kopa was the most successful figure of the period. He took over the team in 1976 when the club was occupying the last rank in the league. The coach took the team to a grouping, also called "The Miracle in Błażejewko", since not only did Lech manage to stay in the league, but also qualified to the international competition and was placed third!

In 1990, 1992 and 1993 Lech won the championship. The club's most exhilarating matches of the last decade all date back to Autumn 1990. Back then the famous Olympique Marseille visited Poznań and lost 2:3. The second leg wasn't as successful since the Frenchmen won 6:1, however a food poising is said to be the reason of Lech's poor performance. Since 1993 and on every next season seemed to be worse than the previous one. Financial troubles forced the club to sell many great players. In 2000 an inevitable degradation took place and Lech left the top league for the first time in 28 years. The first season in the II league was terrible and the team was on the edge of further degradation. However, the year that followed Lech was promoted back to Ekstraklasa. The team from Poznań had one aim: secure a place in the top league. However, the season began poorly. Czesław Michniewicz was appointed as the coach 5 rounds into the season and it turned out to be a great decision since Lech ended the league on the 6th rank and won the Polish Cup, beating Legia Warsaw in the final. Two weeks later the fans celebrated the Super Cup. Although the next seasons weren't as successful, Lech always remained in the top part of the league rank.

Successes came, expectations followed. In 2010/11 Lech was meant to qualify to Champions League group stage. However, Sparta Prague stopped Lech from reaching its aim. The team from Poznan beat Dnipro and advanced to Europa League group phase where Manchester City, Juventus and FC Salzburg were waiting. Lech surprised the whole continent and ended the group phase second, just behind Manchester City. However, due to poor results in the league, Zieliński was replaced by former Barcelona player, Jose Mari Bakero. The great adventure on the European arena ended with a loss to Sporting Braga. The 5th rank in the league did not meet the expectations. In addition, Lech lost in the Polish Cup final to Legia Warsaw.

2011/12 season began really well. Bakero's team came close to the top spot, but gradually the form degraded and a terrible series of lack of goals began. Nevertheless, it wasn't until February 2012 that Bakero was fired. Mariusz Rumak, the assistant coach, replaced the Spaniard. There were little expectations, but the coach led the team to a series of great matches and only in the last round did Lech lose its chance to win the championship. The fourth rank gave Lech a chance to qualify to the European competition. Artiom Rudnev scored 22 goals that season and joined HSV Hamburg in the summer.

The next season began with Europa League qualifications in July. Lech beat the team from Kazakhstan and Azerbaijan, but was stopped by the Swedish AIK Solna. A few days later Lech was eliminated from the Polish Cup by Olimpia Grudziądz. Thus before the season really began, the team from Poznań was fighting on one front only. Nevertheless, Lech completed the highest number of points in away matches, setting a historical record. Poor performances at home meant that the championship slipped through the fingers. The season 2012/13 is considered a historical one since it was the first time ever that Lech was a runner-up in the fight for the national championship.

The next season Lech was placed second too. This time it wasn't perceived as a success, but rather as a failure, since Lech not only lost to team from Vilnius in III Europa League qualification round, but was also eliminated from the Polish Cup by Miedź Legnica.

Next season Lech was humiliated on the international arena by Stjarnan F.C. – a loss that ended Rumak's career as a coach of Lech Poznań and for the next three months Krzysztof Chrobak led the team

On September 1st, 2014 Maciej Skorża was named as the new coach. Despite initial difficulties, the season was a successful one, both on the national and international arena. For the first time in a few years Lech qualified to the final of the Polish Cup. However, what counts the most is the win in the fight for the championship and the opportunity to compete for the Champions League group stage.

Wiosną 2021 lechici wpadli w kryzys, który oznaczał rozstanie na siedem kolejek przed końcem sezonu z trenerem Dariuszem Żurawiem. Tydzień później drużynę poprowadził przeciwko Legii Warszawa (0:0) jego asystent - Janusz Góra. Na trybunach siedział już jednak Maciej Skorża, dla którego był to powrót do Kolejorza po ponad pięciu latach. Ostatecznie poznaniacy zajęli jedenaste miejsce w tabeli, najniższe od 2006 roku, kiedy klub przejęła rodzina Rutkowskich. Nowy szkoleniowiec mógł w ostatnich starciach poznać drużynę i podjąć decyzje kadrowe w kontekście kolejnych rozgrywek.

Dodajmy, że przed tym sezonem w Poznaniu zakontraktowany został napastnik Mikael Ishak, który stał się z miejsca gwiazdą i jednym z ulubieńców kibiców, zapracował zresztą od razu na miano najlepszego strzelca w całej Lidze Europy. Zimą z kolei pojawili się Jesper Karlstrom, Bartosz Salamon czy Antonio Milić, czyli kolejni architekci mistrzostwa Polski 2022.

Latem 2021 klub wkroczył w sezon, w trakcie którego były obchody stulecia oficjalnej rejestracji. Urodziny musiały być szczególne i były! 19 marca 2022 roku przy Bułgarskiej odbył się mecz rocznicowy z Jagiellonią Białystok (3:0), który miał szczególną oprawę. Przed pierwszym gwizdkiem sędziego Liber zaśpiewał odświeżoną wersję piosenki „Czysta gra”, która powstała, kiedy klub miał 85 lat. Na murawie obie ekipy wystąpiła w strojach retro, nie zabrakło też specjalnej iluminacji rocznicowej. Były też inwestycje w infrastrukturę - największą w historii inwestycją była budowa Centrum Badawczo Rozwojowego Akademii Lecha we Wronkach.

Najważniejsze było jedna to, co na boisku. Kolejorz prowadzony przez trenera Macieja Skorżę, który wywalczył wcześniej mistrzostwo w 2015 roku, od początku sezonu był w ścisłej czołówce. Przez wiele kolejek był liderem. Nie brakowało jednak dramaturgii. Długo prowadzący Lech stracił pozycję lidera na rzecz Rakowa Częstochowa, który na trzy kolejki przed końcem miał wszystko w swoich rękach. 2 maja obie ekipy spotkały się na Stadionie Narodowym w Warszawie w finale Pucharu Polski, częstochowianie wygrali 3:1 i sięgnęli po trofeum. Kluczowa w ekstraklasie była jednak seria 32. W niedzielę 8 maja najpierw Raków zremisował z Cracovią (1:1), a chwilę potem grał Kolejorz, który wykorzystał swoją szansę. Ograł w Gliwicach Piasta 2:1, gola na wagę trzech punktów Mikael Ishak wbił w 88. minucie, co wywróciło tabelę. Tydzień później wszystko było już jasne, to lechici cieszyli się z tytułu, bo wygrali w Grodzisku Wielkopolski derby z Wartą Poznań (2:1). Przyjechali na Bułgarską i obejrzeli ostatnie 20 minut starcia w Lubinie, gdzie Zagłębie w doliczonym czasie trafiło z Rakowem na 1:0 i w tym momencie stało się jasne, że złoto trafi do Poznania.

Spontaniczna feta obyła się 14 maja przed stadionem, a ta oficjalna z wręczeniem pucharu i medali tydzień później. Spójrzmy na serię sześciu kolejnych wygranych lechitów na finiszu. Kolejno ograli wówczas: Wisłę Płock (1:0), Górnika Łęczna (3:0), Stal Mielec (3:1), Piasta Gliwice (2:1), Wartę Poznań (2:1) oraz Zagłębie Lubin (2:1). Ba, niebiesko-biali byli o włos od klubowego rekordu kolejnych wygranych! Jak to możliwe? Nie przegrali w ostatnich dziewięciu kolejkach - zdobyli w nich 25 na 27 możliwych punktów. Jedyny remis był z Legią Warszawa (1:1) przy Bułgarskiej w meczu, w którym w doliczonym czasie gry należał się gospodarzom rzut karny. Gdyby został podyktowany, a jedenastka wykorzystana, to drużyna trenera Skorży wyrównałaby rekord należący do Adama Topolskiego i Lecha z jesieni 1998 - wtedy zaliczył on właśnie dziewięć kolejnych triumfów i ten wynik do dziś jest rekordowy.

Sezon 2022/2023 rozpoczął się jak w filmie Alfreda Hitchcocka - od trzęsienia ziemi. Po mistrzowskim sezonie odszedł bowiem trener Maciej Skorża, którego zastąpił holenderski szkoleniowiec John van den Brom. Miał bardzo mało czasu na zapoznanie się z nową drużyną. Sezon dla Kolejorza rozpoczynał się bowiem wyjątkowo wcześnie, bo już 5 lipca.

Wtedy bowiem startowały eliminacje Ligi Mistrzów, w których niebiesko-biali trafili na Karabach Agdam. Przy Bułgarskiej było 1:0 po golu niezawodnego Mikaela Ishaka, a w rewanżu - bolesna porażka 1:5 w Azerbejdżanie. Nie ma jednak tego złego, co by na dobre nie wyszło. Rozpoczęła się bowiem niesamowita przygoda pucharowa, która trwała blisko dziesięć miesięcy i zaprowadziła Lecha do historycznego europejskiego wyniku, bo pierwszy raz klub znalazł się w ćwierćfinale.

Było to w Lidze Konferencji Europy, do której zespół doprowadziło wyeliminowanie gruzińskiego Dinamo Batumi (5:0, 1:1), islandzkiego Vikingura Reykjavik (0:1, 4:1 po dogrywce), a także luksemburskiego F91 Dudelange (2:0, 1:1). W fazie grupowej wywalczyliśmy dziewięć punktów, a awans dała efektowna listopadowa wygrana nad hiszpańskim Villarreal CF (3:0) po dwóch golach Michała Skórasia, a także jednym Kristoffera Velde. Lechici sami wzięli sprawy w swoje ręce, bo przed ostatnią kolejką wiedzieli, że uzyskają promocję, jeśli wygrają. Wtedy nie musieli się oglądać na konfrontację izraelskiego Hapoelu Beer Szewa z Austrią Wiedeń. W fazie play-off los skojarzył z norweskim Bodø/Glimt. Na wyjeździe był bezbramkowy remis, a przy Bułgarskiej 1:0 po trafieniu niezawodnego Ishaka, który w trakcie sezonu przedłużył kontrakt z Lechem i pracuje w nim na miano legendy. W trakcie poprzednich rozgrywek ścigał najskuteczniejszego do tej pory obcokrajowca w historii Kolejorza - Duńczyka Christiana Gytkjaera.

Lech stał się pierwszym polskim klubem od 32 lat, który wyeliminował rywala wiosną w europejskich pucharach. I poszedł za ciosem, bo wyrzucił za burtę także kolejnego, co pozwoliło wyrównać osiągnięcie Górnika Zabrze sprzed ponad pół wieku. W dwumeczu 1/8 finału nie pozostawił wątpliwości szwedzkiemu Djurgårdens IF (2:0, 3:0). W walce o półfinał wpadł na włoską Fiorentinę - w Poznaniu było 1:4, a w rewanżu we Florencji po nieco ponad godzinie gry piłkarze trenera Broma prowadzili 3:0, co wprawiło w osłupienie przeciwników oraz miejscowych kibiców. Włosi jednak wbili w końcówce dwa gole i zakończyli piękną przygodę Lecha.

Zespół rozegrał w sezonie 2022/2023 aż 56 meczów! Oprócz 34 w PKO BP Ekstraklasie, także 20 w europejskich pucharach oraz po 1 w walce o Superpuchar i w Pucharze Polski. Te 20 w międzynarodowych rozgrywkach to rekord w jednym sezonie w całej Europie, Kolejorz wyrównał osiągnięcie kilku innych zespołów. Potrafił też w tym maratonie połączyć puchary i ligę, w której zajął trzecie miejsce po emocjonującym finiszu.