United rubber stamped a fifth placed finish with a comfortable and eye-catching performance in the last match of an extraordinary Premier League season.
In a hastily re-arranged fixture played in front of an understandably sparse crowd, Wayne Rooney put United ahead with his 100th goal at Old Trafford before new England call-up Marcus Rashford doubled the lead and substitute Ashley Young made it three late on.
Max Gradel- via a hefty deflection off Chris Smalling- grabbed the visitors first ever goal at United late on as the Cherries finish 16th in their maiden top flight campaign.
Michael Carrick- in what could be his final league appearance for United- went close from a Rooney free-kick before Marc Pugh had an effort blocked by Antonio Valencia at the other end.
Chances were at a premium in the first half but the breakthrough arrived two minutes shy of the interval with one of the best goals seen at Old Trafford this term.
Rooney started and finished the move as he picked out Juan Mata with a sublime cross-field pass and the Spaniard fed Anthony Martial who crossed for Rooney- after a neat dummy by Rashford- to slot in from close range.
Dan Gosling lashed over from distance and Callum Wilson went close with a snapshot, but United should have had a penalty on 50 minutes when Mata was clearly fouled by Steve Cook but referee Jonathan Moss waved play on.
Michael Carrick had an effort deflected on to the bar, Jesse Lingard fired just off target and Valencia's piledriver was tipped over by Adam Federici in a flurry of chances from the hosts.
Federici saved well from Mata and Smalling headed wide but the chances kept coming and United finally doubled the advantage 16 minutes from time.
Rooney's pinged pass picked out Valencia who cushioned the ball for Rashford to sweep home his eighth of the season in front of the Stretford End.
Playing in midfield, Rooney was simply outstanding and was involved again as United moved further ahead three minutes from time.
Substitute Young latched on to a fine through ball from the skipper and applied the finish for his first Reds goal since last April's Manchester derby victory.
Despite an unfortunate injury-time own goal from Smalling- the final league goal of the season- it proved to be merely a consolation for Eddie Howe's side as United warmed up for Wembley with a comfortable victory.
Overall team performance: 7.5/10
United Faithful Man of the Match: Who else but Wayne Rooney. Scored one and created the other two. Magnificent.