A bullocking Aaron Woods try put NSW ahead midway through the second half 20-18, before a 70th minute Josh Dugan effort clinched NSW the win after their narrow game one loss.
Dugan's effort came after Mitchell Pearce was denied a 65th minute try and a Greg Inglis four-pointer was turned down minutes later.
Referee Ben Cummins ruled that the final pass from Trent Hodkinson as forward before Pearce loped over, the video referee then deciding Michael Morgan knocked on in the lead-up to Inglis' 80m effort.
"It was a brutal game," Jennings told Channel Nine.
"We took it up the middle all night.
"I was lucky there with the try and just grateful for the opportunity and it's good to have a win with the boys."
Jennings opened the scoring for NSW before Queensland had even touched the ball and the Blues led 6-0 after as many minutes before 91,513 fans, a record Origin crowd for the MCG.
Matt Scott barged his way over five minutes later and the scores were tied.
Shortly after the first melee of the match Josh Morris latched onto a Pearce cross kick and NSW led 12-6 after 26 minutes. A penalty goal just before the break put NSW ahead 14-6.
Soft Blues defence allowed Matt Gillett a try in the 49th minute and the game entered a short lull before Woods barged over the top of Scott and Hodkinson's conversion put the Blues ahead 20-18.
Pearce and Inglis' tries were then denied before Dugan surged over for NSW to lock up the series at 1-1.
NSW's outside backs outpointed their opponents and the Blues were dominant up front with Woods and good mate David Klemmer instrumental.
"We said we wouldn't take a step back against the big boys of Queensland," Woods said.
"The try was the best ever, I couldn't believe I got over."
Queensland skipper Cameron Smith said he thought the Inglis try was good.
"It was a 50-50 call. I thought it went backwards, but I'm wearing a Maroon jersey," he said.
"We lost our way a couple of times. The effort's been great but we have to fix some execution things.
"Unfortunately it wasn't our night. I thought it was a pretty good game of footy and it was a great atmosphere with 91,000."
Blues skipper Paul Gallen could be in doubt for Origin III on July 8 in Brisbane after suffering rib cartilage damage in the first half. Gallen left the field for a pain killing injection before returning.
Justin Hodges could also be in some strife after hitting Ryan Hoffman high in a first half tackle that sent the Blues back-rower from the field for a concussion scan, before he too returned.
Johnathan Thurston was Queensland's best without halves partner Cooper Cronk, who missed the match with a knee injury but is expected to be fit for Origin III.
