The 1979–80 FA Cup was the 99th season of the world's oldest football knockout competition, The Football Association Challenge Cup, or FA Cup. The final saw second division West Ham United beat holders Arsenal 1-0. As of 2012, this was the last occasion when a club outside the top division of English football won the FA Cup.

The first round of games were played on 24 November 1979. Replays were played on 26–28 November.

The second round of games were intended to be played on 15 December 1979, but some matches were not played until 17–19 December and one until 5 January 1980. Replays took place at various dates after these games.

The third round of games in the FA Cup were mainly played on 5 January 1980, with some games taking place on 8–9 January and one on 14. Replays were intended for the 8–9 January but again took place at various times.

The fourth round of games were mainly played on 26 January 1980. Replays were played on 29 and 30 January.

The fifth set of games were all played on 16 February 1980. Two replays were played on 19 and 20 February.

The Football Association Challenge Cup, commonly known as the FA Cup, is a knockout cup competition in English football and is the oldest association football competition in the world. The "FA Cup" is run by and named after the Football Association and usually refers to the English men's tournament, although a women's tournament is also held. Its current sponsored name is the FA Cup with Budweiser.

The FA Cup was first held in 1871–72. Entry is open to all teams who compete in the Premier League, the Football League and in steps one to five of the FA National League System, as well as selected teams in step 6. This means that clubs of all standards compete, from the largest clubs in England and Wales down to amateur village teams. The tournament has become known for the possibility for "minnows" from the lower divisions to become "giant-killers" by eliminating top clubs from the tournament and even theoretically winning the Cup, although lower division teams rarely progress beyond the early stages. The qualification rounds and a system of byes mean that the very smallest and very biggest teams almost never meet.

Liam Brady (born 13 February 1956) is an Irish former association football player, and former assistant manager of the Republic of Ireland national football team.

In his playing days, Brady was a midfielder renowned for his elegant technical skills, most notably his left foot, and his high-quality passing and close control. He found success both with Arsenal (one FA Cup title) and Juventus (two Serie A titles), and won 72 caps for the Republic of Ireland national football team.

Brady is now head of Youth Development at Arsenal, and is a frequent television pundit with RTÉ Sport.

Born in Dublin, Brady started his career at Arsenal, moving to London to join the side on schoolboy forms in 1971, at the age of 15. He turned professional on his 17th birthday in 1973, and made his debut on 6 October 1973 against Birmingham City as a substitute for Jeff Blockley, and put in an assured performance. However his next match, in a North London derby against Tottenham Hotspur, Brady had a poor match, and Arsenal manager Bertie Mee decided from then on to use the young Irishman sparingly for the time being. Brady ended the 1973–74 season with 13 appearances (four of them as substitute) to his name.

Ian James Rush, MBE, (born 20 October 1961 in Flint) is a Welsh former footballer. He is best remembered as a player for Liverpool, where he was among the top strikers in the English game in the 1980s and 1990s. He also had spells playing at Chester City, Juventus, Leeds United, Newcastle United, Sheffield United, Wrexham and Sydney Olympic. Rush made 73 appearances for the Wales national football team and he remains the record goalscorer for Wales with 28 goals between 1980 and 1996.

Since retiring as a player in 1999, Rush has had a stint as manager of Chester City (2004–05), and has worked as a television football pundit. He was also very well known for his moustache.

Rush's reputation was enhanced by scoring for Chester in a shock 2–0 FA Cup third round win at Second Division giants Newcastle United in January 1980, with Chester equalling their best run by reaching the last 16 where they narrowly lost to Ipswich Town two rounds later. His last game for Chester was a 2–1 win over Southend United at Sealand Road on 26 April 1980 in which he did not score.