Bosnich was signed for Manchester United in the 1999 close season as successor to Peter Schmeichel, signing on a free transfer after his contract at Villa Park expired. During the season, he picked up a Premier League title medal as United were crowned champions by an 18-point margin. That season Bosnich started 23 league games, Raimond van der Gouw started 11 and Massimo Taibi started 4. Highlights of this season was saving two penalties in January 2000; one from Necaxa's Álex Aguinaga in the 2000 FIFA Club World Championship to secure a 1–1 draw, and the other from Middlesbrough's Juninho to help secure a 1–0 win. He also played a key role in Manchester United becoming the first English team to win the Intercontinental Cup in keeping a clean sheet against Palmeiras of Brazil, in Tokyo.