The 1990–91 season was Manchester United's 89th season in the Football League, and their 16th consecutive season in the top division of English football.
After winning the FA Cup the previous year to end a five-year trophy drought and claim their first major trophy under the management of Alex Ferguson, United went on to achieve more success by lifting the European Cup Winners' Cup – their first European trophy since their European Cup triumph 23 years earlier – by beating Barcelona 2–1 in Rotterdam, with Mark Hughes scoring both goals. It was the first season back in European competitions for English clubs following the lifting of the ban which had been imposed back in 1985 due to the Heysel Stadium disaster.
Hughes was voted PFA Player of the Year, while promising young winger Lee Sharpe was voted PFA Young Player of the Year. Fellow winger Ryan Giggs, aged 17 and said to be the club's finest young prospect since George Best, signed a professional contract in late November, and soon broke into the first team, making two league appearances and scoring one goal. A new arrival at the club was full-back Denis Irwin, signed from Oldham Athletic for a fee of £625,000 in the close season. Following his impressive performance in the previous season's FA Cup final replay, Les Sealey's loan move became permanent on a one-year contract, and he was the club's first choice goalkeeper for the season, but left on a free transfer at the season's end and signed for Aston Villa.
United also reached the League Cup final for the second time, but suffered a shock defeat to Sheffield Wednesday (managed by former United boss Ron Atkinson). In the league, United improved upon the previous season's 13th-place finish, but erratic form meant that they failed to mount a title challenge and finished sixth and were below neighbours Manchester City for the first time since 1978. Their defence of the FA Cup ended in the Fifth Round when they lost 2–1 to Norwich City.
Assistant manager Archie Knox resigned late in the campaign to take the same role at Rangers, and was replaced by Brian Kidd.
It was the final season at Old Trafford for veteran defender Viv Anderson, who had failed to reclaim his place in the first team and was sold to Sheffield Wednesday in January 1991. Winger Ralph Milne, who had not played a first team game for the club for nearly two years, was given a free transfer at the end of the season. Colin Gibson, who had rarely been selected since the 1988–89 season, was sold to Leicester City just before Christmas.
Goalkeeper Gary Walsh, who stood in for the injured Les Sealey in several late season games, made his first appearances for United in three years.
Lee Martin, the hero of the previous season's FA Cup final, suffered a back injury and appeared in less than half of the season's games, as Alex Ferguson chose Denis Irwin as his regular right-back and Clayton Blackmore as his regular left-back. Striker Mark Robins, another star of the cup run, had a less successful season, with fewer first team opportunities and just five goals in all competitions, despite some promising performances in the autumn.
