Josh King scored his fourteenth goal of the season in just the second minute for Eddie Howe's team, and that early goal foreshadowed what was to come.
Bournemouth's dominance continued through the first-half and Benik Afobe netted their second of the game.
Gastón Ramírez's red card in the 20th minute looked to spell the end to any hope that Middlesbrough had of salvaging anything from the match, with 70 minutes still to play.
The second half was no better than the first for Steve Agnew's Boro and Bournemouth went on to score twice more through Marc Pugh and Charlie Daniels to ensure that Boro lost their 16th game this season.
The result leaves Middlesbrough's chances of survival slim, with nine points separating them and 17th although they have a game in hand on their relegation-battling rivals.
Bright Bournemouth start
Despite Boro being stuck in the relegation zone, it was the Cherries who started this game with a sense of urgency as King put Bournemouth ahead in just the second minute of the match.
The Norwegian international received the ball from Pugh and slotted the ball past Brad Guzan in the Boro goal.
Howe's men kept their foot on the gas and doubled their lead in the 16th minute, as Clayton lost the ball in his own half and let in Afobe to calmly slide the ball past Guzan and into the back of the net.
Ramírez sees red as Boro's woes double
Middlesbrough's problems were only made worse in the 20th minute as Ramírez, who had been booked for a blatant dive just minutes earlier, received his marching orders following a lunge through the back of Pugh.
Agnew will have been thinking that his luck could not get any worse when he was forced into another early substitution. After changing formation following Gaston's red card, Marten de Roon was forced to leave the pitch with an ankle injury.
An eventful first period ended with a touching moment as the Vitality Stadium rose in the 44th minute to applaud the life of Ugo Ehiogu, who passed away yesterday at the age of 44.
There had been a minute's applause before kick-off, but this more spontaneous tribute to the former Boro defender was telling of the impact he had on the people of Teesside.
Despite this great tribute from the Middlesbrough faithful, the fans had nothing else to smile about during the first-half.
Unfortunately, nothing changed in the second-half for the fans who had traveled 300 miles to the South Coast.
Much of the same in the second period
Bournemouth had the best chance of the second half in the 56th minute as Afobe stooped to head the ball, but Guzan made a sharp save down to his right-hand side.
Pugh puts Bournemouth three goals to the good in the 65th minute. Middlesbrough gave the ball away extremely poorly after trying to start a counter attack. The Cherries' winger collected the ball and curled it into the bottom corner.
Just five minutes later, and Bournemouth had picked apart the poor Boro defence again and it was left-back Daniels who put his name on the score sheet.
Despite their team suffering their worst defeat of the season and offering nothing going forward, the fans from Teesside were still singing - though there was little to sing about.
Afobe missed the chance to put the cherry on the cake as the ball fell to him at the back post but he could not put it into the net.
Chants of 'You're Going Down' rang around the stadium to taunt the feeble Boro players, who put up no fight in this match. They still sit in 19th place in the Premier League table and are now nine points from safety.
Bournemouth's win lifts them to 12th place in the table and they look to have answered any questions about their league status with a seven-point gap distancing them from relegation fears.