Rovers made it four top-half finishes in the last five years as they came away from Villa Park with a 1-0 win courtesy of Richard Dunne's own goal six minutes from time.
The result followed last Monday's 2-1 victory over Arsenal and means Allardyce's side were beaten just once in their last nine games, a satisfying conclusion to the season which has boosted the prize money they will receive for their final position.
"Arsenal 2-1 and Aston Villa 1-0 - it's a fantastic finish to the season for us and shows you the difference that a couple of wins makes," Allardyce said.
"Instead of perhaps 14th in the table, which we would have been quite satisfied with, we have now beaten two of the big guns in the Premier League.
"It will hopefully make a big difference to our budget in the summer."
Dunne wrapped up the points for Rovers when he attempted to head away Martin Olsson's dangerous cross, beating Junior Hoilett to the ball but inadvertently directing it past Brad Friedel and in.
Allardyce was delighted to see his team selection rewarded, having decided to give a run-out to several youngsters, including debutants Grant Hanley and Amine Linganzi.
"It was nice to not have to worry about the result too much - even though we wanted the money - and to play younger players again," Allardyce said.
"To give them a taste of the Premier League against an Aston Villa side that was at full-strength, I knew it was going to be very difficult today and certainly in the first half, it was.
"But we battled our way through and when we changed the system a little bit and got a bit more forward movement, we finally caught them on the break with a terrific goal."
Despite the defeat, Villa hung on to sixth spot thanks to Hull's goalless draw with seventh-placed Liverpool at the KC Stadium.
That means Martin O'Neill's side will not have to play an extra round in next season's Europa League.
Villa beat Newcastle to keep Hull up on the final day a year ago and O'Neill was grateful to the Tigers for returning the favour.
"It was a disappointing result, but I'm delighted we finished sixth," O'Neill said.
"That was our aim this morning. I think we gave Hull a bit of help last year on the last day of the season, so I'm delighted they have reciprocated.
"I'm disappointed with the result, but not with the season or our position.
"I thought we played some good stuff in the first half and was hoping that we would take it on in the second half.
"But Blackburn came out with a bit of renewed vigour and penned us back. Overall I think they probably had the better of the second half."
Reports have suggested Liverpool boss Rafael Benitez could be on his way out of Anfield this summer, with O'Neill touted as the leading candidate to succeed him - while Croatia coach Slaven Bilic has in turn been linked with Villa.
O'Neill moved to dismiss the speculation surrounding his future last week by insisting that he wants to stay at Villa Park.
When asked on Sunday if he thought he would still be with Villa for the first game of next season, he asked the reporter directing the question: "Could you tell me where you are going to be in three, four or five months' time?"
O'Neill was more emphatic in his response when asked if the club was still a special place to be and if his was still a special job to have.
"Without a doubt," O'Neill said.
"Aston Villa is a remarkable club and there is not much more I can add to that."