On 8 January 2009, De Laet was signed by Premier League champions Manchester United on a three-year contract. The fee to be paid by Manchester United depended on appearances. After joining United, De Laet played exclusively for the club's reserve team. In March 2009, De Laet was named as one of five over-age players in the Manchester United under-18 squad for the Torneo Calcio Memorial Claudio Sassi-Sassuolo; he played in three of the five matches, and scored a penalty in the 5–3 semi-final penalty shoot-out win over Modena to take the Red Devils into the final, in which they beat Ajax 1–0.