On this display Boro could achieve their target of a top-eight finish with more than 52 points.
Southampton were simply outclassed as Middlesbrough recorded their fourth home win in a row. It was essentially a team triumph but the game will be remembered as the one in which Italian striker Massimo Maccarone finally won over the hearts of Boro fans.
Maccarone, so often labelled an extensive misfit in his two-season spell at the Riverside Stadium, finally showed glimpses of the form that prompted manger Steve McClaren to splash out a record club fee of £8million.
Maccarone was a revelation in a side with so many talented individuals. Southampton could have no grumbles over the scoreline because they were second best virtually from the start.
The Saints struggled to make any impression in attack. Indeed the consolation goal came from a mistake by Middlesbrough's Australian international goalkeeper Mark Schwarzer.
Middlesbrough fully deserved a standing ovation from the 30,000 crowd at the final whistle.
Boro welcomed back Danny Mills and Boudewijn Zenden while Southampton included former Sunderland striker Kevin Phillips.
Philips was linked with Boro last summer before McClaren decided that midfield was his priority and Phillips moved on to Southampton.
Phillips no doubt wanted to maintain his recent impressive scoring run to show Boro fans what they had missed. However, he was blotted out by a strong defence.
Boro went ahead when Brazilian star Juninho crashed the ball into the roof of the net for his ninth goal of the season.
Szilard Nemeth pulled the ball back form the right and Juninho left Antti Niemi helpless with a shot from six yards.
Middlesbrough fans were certainly enjoying the best attacking display of the season at the Riverside Stadium.
So often described as boring and negative in the first half of the season Middlesbrough have hit a rich seam of form.
Nemeth increased the lead after 32 minutes when the lively Maccarone won a challenge against Claus Lundekvam following a pass by Gaizka Mendieta.
Niemi made an attempt at a clearance but the ball ran to Nemeth and the Slovakian international slotted home his fourth goal in seven games.
Five minutes after the break Boro went further ahead when Maccarone fired a ground shot into the net following good work by Franck Queudrue.
Southampton struggled to make an impression in attack although they reduced the arrears after 70 minutes.
Schwarzer half-punched the ball across his own penalty area for James Beattie to take full advantage with a shot into the net.
Middlesbrough: Schwarzer, Queudrue, Mills, Ehiogu, Cooper, Mendieta (Greening 86), Boateng, Zenden, Juninho Paulista (Ricketts 89), Nemeth (Downing 82), Maccarone. Subs not used: Jones, Bates.
Southampton: Niemi, Telfer, Lundekvam, Higginbotham, Crainey, Prutton, Delap (Anders Svensson 81), Folly, Fernandes (Pahars 56), Phillips, Beattie. Subs not used: Smith, Hall, Ormerod.
Attendance: 30,768.
Referee: D Gallagher (Oxfordshire)