Britt Assombalonga’s close range header in the 19th minute - his 12th strike of the season - was ultimately enough for Tony Pulis and his side, who produced a dominant first-half performance to provide the platform to victory.
Their task was helped by Derrick Williams, who was sent off just before half-time, and Boro would have added to the scoreline but for the woodwork and superb goalkeeping.
Rovers registered one shot on target - but an excellent Darren Randolph save denied Bradley Dack.
Boro’s third victory in their last four away games puts them firmly in the play-off picture - and they won’t be giving up on automatic promotion any time soon.
Their victory heaped the misery on former player and manager, Tony Mowbray, whose side are now firmly mid-table after a fourth consecutive league defeat - the first time this has happened under his stewardship.
Former Boro striker Danny Graham made his 100th league start for Blackburn, one of four changes after the defeat at Reading.
Middlesbrough were forced into a defensive reshuffle following injury to Aden Flint and Daniel Ayala’s suspension and Assombalonga was restored to the starting XI after the loss at Sheffield United.
The visitors started brightly, with Ashley Fletcher heading straight at David Raya, and he was involved in the 19th minute as Boro took a deserved lead.
Fletcher latched onto a long ball and although his low drive was deflected - seemingly wide - Assombalonga was following in and had the simple job of heading into an empty net.
Lewis Wing curled narrowly over soon after, but Rovers did not help their own cause on the stroke of half-time, when Williams was sent off for bringing down Fletcher on the edge of the area when he was clean through.
Rovers tried to freshen things up at half-time but were almost further behind within minutes of the restart through Wing’s dipping 25-yard shot, which clattered the crossbar with Raya beaten.
Boro went even closer 20 minutes from time when Jonny Howson’s effort from out wide looked to be heading in but Raya did magnificently well to tip the ball over.
The game became stretched as time wore on, with Graham blazing over an excellent chance from eight yards, before Fletcher shot meekly at Raya.
Dack thought he had equalised seven minutes from the end when he caught the ball crisply on the half-volley from close range but Randolph produced a stunning save to deny him.
The visitors responded on the break and Assombalonga’s fine low strike was thwarted through Raya, who showed excellent reflexes to get a hand on the shot and tip over the loose ball.
However, one goal proved enough for Pulis and his team.