Sammie Szmodics' double strike gave Blackburn a vital win as they marked the 5,000th league game in their history.
The midfielder scored in either half to keep Boro anchored to bottom spot with five defeats from six.
Matt Crooks gave Boro hope with a goal in an end-to-end game in which both teams missed a host of chances.
Rovers became only the seventh English club to play 5,000 league games, and moved up to eighth.
They celebrated by parading a string of past legends on the pitch, and EFL chairman Rick Parry presented the club with a commemorative trophy before kick-off.
Jon Dahl Tomasson's team set about celebrating the moment in style and should have been out of sight by half-time against a Boro side struggling defensively.
Tyrhys Dolan and Darragh Lenihan missed sitters at either end of the opening 45 minutes, but Szmodics found the accuracy that deserted his team-mates and opened the scoring when given time to weigh up his shot from outside the box.
Boro keeper Seny Dieng denied Rovers a second straight from the restart, but as the visitors sought to hit back they were caught on the counter and Szmodics drilled home his second from Ryan Hedges' square pass.
That brought a response from Michael Carrick's beleaguered team as Crooks backheeled Marcus Forss' shot home, and suddenly it was Rovers on their heels.
Summer signing Emmanuel Latte Lath missed two great chances for the away side, Rav van de Berg contrived to head another opportunity over the bar, and sub Riley McGree fired inches too high.
Rovers also had their moments to seal the win, notably when Dieng superbly denied Szmodics.
Blackburn manager Jon Dahl Tomasson told BBC Radio Lancashire:
"It's a fantastic result. It was great to see the amount of chances we created. We should probably have been 3-0 up at half-time.
"The frustrating part is that we haven't converted those chances into goals, then we scored a very difficult goal. The second one was also difficult - great goals.
"Middlesbrough then got a goal and it can be tough, but our fans helped us through that period of the game.
"It was great for Rovers to win their 5,000th league game. Great history, and seeing all those legends in the stadium - I hope they enjoyed it.
"Sammie could have had a hat-trick and he played a great game. His link-up play, he scores goals, and he will run through walls for the team."
Middlesbrough manager Michael Carrick told BBC Radio Tees:
"It was a little bit chaotic at times, at both ends, and we played some really good football at times.
"They were dangerous at times and we had 19 or 20 shots at goal. Again, it didn't go for us but for all the positives we can take from it, which we will, there's still the element that we can do better.
"There's no hiding from the fact we haven't had good results so it's not like the boys have come in full of belief and bouncing with confidence.
"I can't fault the players. They weathered the storm early, grew into the game, the belief grew, we had another setback just after half-time and we came back into it again and gave everything we have got.
"There are moments in games when we haven't helped ourselves but I don't think the performances have been that bad."