The 2006 Football League Championship play-off Final was an association football match which was played on 21 May 2006 at the Millennium Stadium, Cardiff, between Leeds United and Watford. The match was to determine the third and final team to gain promotion from the Football League Championship, the second tier of English football, to the FA Premiership. Reading and Sheffield United, the top two teams of the 2005–06 Football League Championship season, gained automatic promotion to the Premiership, while the clubs placed from third to sixth place in the table took part in play-off semi-finals. Third-placed Watford defeated sixth-placed Crystal Palace in the first semi-final, while fifth-placed Leeds United beat fourth-placed Preston North End. The winners of these semi-finals competed for the final place for the 2006–07 season in the Premiership. Winning the final was estimated to be worth up to £40 million to the successful team.

Leeds United Football Club is a professional football club based in Leeds, West Yorkshire in England. The club play their home matches at Elland Road and compete in the Championship, the second level of the English football league system.