The following are the football (soccer) events of the year 1921 throughout the world.

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• September – There is a split in Irish football following the political partition of Ireland. The leading Dublin clubs breakaway from the Belfast-based Irish Football Association over a perceived northern bias. See:FAI – Split from the IFA^[1]

• Argentina: Club Atlético Huracán, Racing Club
• Austria: Rapid Vienna
• Belgium: Daring CB
• Denmark: Akademisk Boldklub
• England: Burnley F.C.
• France: no national championship
• Germany: 1. FC Nürnberg
• Hungary: MTK Hungária FC
• Iceland: Fram
• Italy: Pro Vercelli
• Luxembourg: Jeunesse Esch
• Netherlands: NAC Breda
• Paraguay: Club Guaraní
• Poland: Cracovia
• Scotland: For fuller coverage, see 1920–21 in Scottish football.
  • Scottish Division One – Rangers
  • Scottish Cup – Partick Thistle^[2]
• Sweden: IFK Eskilstuna
• Uruguay: Peñarol
• Greece: 1913 to 1921 – no championship titles due to the First World War and the Greco-Turkish War of 1919–1922.

• FK Željezničar

• 1921 British Home Championship (October 23, 1920 – April 9, 1921)

 Scotland

• 1921 Far Eastern Championship Games in China (May 30-June 2, 1921)

China

• South American Championship 1921 in Argentina (October 2, 1921 – October 30, 1921)

 Argentina

• February 10 – Theodor Reimann, Slovak international footballer (died 1982)
• May 12 – Cor van der Hoeven, Dutch footballer (died 2017)
• May 23 – Wilf Chisholm, English professional footballer (died 1962)^[3]
• July 26 – Amedeo Amadei, Italian international footballer and manager (died 2013)
• August 1 – Percy Lovett, English footballer, goalkeeper (died 1982)
• October 6 – Des Broomfield, English footballer (died 2007)^[4]
• October 19 – Gunnar Nordahl, Swedish international footballer (died 1995)
• November 11 – Ron Greenwood, English football manager (died 2006)

Undated:

• Arie Machnes, Israeli footballer (died 2008)

• Deportivo Alavés