Dennis Bergkamp scored his last Arsenal goal as the Gunners paid tribute to their long-serving striker at Highbury.
The day was dubbed "Bergkamp Day" and Arsenal's stadium was awash with orange, the colour of the Dutchman's national team.
West Brom's Nigel Quashie had cancelled out Aliaksandr Hleb's opener, but Bergkamp came off the bench and played a part in Robert Pires's goal before scoring himself in the 89th minute.
Manchester United reestablished a five-point lead over Manchester City at the Premier League summit with a 4-0 win at Old Trafford.
Two goals from Wayne Rooney along with strikes from Danny Welbeck and Nani meant the Red Devils looked well-placed to end the campaign with a 13th PL title.
But they dropped five points in their next two matches, which included a loss at Man City, as their local rivals were crowned champions on the final day on goal difference.
The 4-0 defeat for Villa left them 15th, a place higher than they would ultimately finish.