In a decider for the ages at Accor Stadium on Sunday, the Broncos came from 22-12 down at halftime to stun the Storm and claim their first premiership since 2006.
Brisbane completed the comeback without Adam Reynolds who limped off in the second half, before halves partner Ben Hunt also suffered a concussion with eight minutes left.
Ezra Mam stepped up for the Broncos with a try assist and a big defensive play swinging the match, after a year where he has dominated headlines for the wrong reasons.
But ultimately it was Walsh who was the hero, with his electric attack and never-say-die defence outdoing a superb first half from Melbourne's all-star big four.
The Brisbane star beat five men to score a superb first-half try, set up three others and produced three try-saving plays to take the Broncos to their seventh premiership.
"I've never seen an individual dominate a grand final like that," Lockyer told AAP.
"Nathan Cleary did it a couple years ago, but that's one of the best individuals performances.
"We talk about his speed and flashiness, but tonight it's toughness, especially. He's such a team-focused person. He does all this stuff to help the team win!'"
Walsh's outing was a fitting end to a finals series he has dominated, having also saved Brisbane against both Canberra and Penrith.
But as good as his finish was in the 94-minute epic against the Raiders earlier this month, Sunday night was even more special.
With Brisbane trailing by 10 at the break, Walsh kept the Broncos in the match when he first scrambled to stop Tui Kamikamica getting a ball down.
From the next set, Mam sent Gehamat Shibasaki over on the left edge, breathing life back into the game.
Walsh then unleashed three minutes of attacking brilliance, with his quick hands first sending Deine Mariner over with a cut-out ball to make it a two-point game.
Brisbane then had the lead when Walsh got the ball, accelerated and threw another cut-out ball for Shibasaki to grab his second with 23 minutes to play.
Then with Melbourne fighting to take back the lead, Walsh produced two more try-saving plays to keep the Broncos on top.
The fullback first chased down opposite number Ryan Papenhuyzen when he broke from a scrum, before another last-line-of-defence tackle on the Storm No.1 in the dying minutes.
"That was definitely up there," Broncos coach Michael Maguire said of Walsh.
"He was outstanding.
"He saved five tries out there, phenomenal. Right to the death, which is the spirit of this team."
Brisbane's efforts to hold on came after they capitulated in similar circumstances two years ago against Penrith, as well as back in 2015 at the death against North Queensland.
But they were a different team on Sunday, holding on until the siren and amid more drama with Melbourne lock Trent Loiero sin-binned late for a shoulder charge.
Earlier, Walsh was the shining light for Brisbane in a first half dominated by Melbourne.
The No.1 laid on the fastest grand-final try of the NRL era when he burst onto a ball in the fourth minute, bust through Jack Howarth and sent a cut-out ball Mariner's way.
But Melbourne led 16-6 through a brilliant 15 minute spell from Harry Grant, Cameron Munster, Jahrome Hughes, Eliesa Katoa and Papenhuyzen.
And while Walsh's superb 30-metre try reduced the margin, Hughes appeared to have Melbourne on their way to a title when he scored to make it 22-12 at halftime.
Ultimately though the Storm made too many poor choices in the second half, and were left to settle for a second straight grand-final loss after last year's defeat to Penrith.
"It's tough losing a grand final, whatever the situation, and certainly with the lead we had," coach Craig Bellamy said.
"When Kamikamica lost that ball over the line, that was a big turning point.
"We would have liked to have won, but we haven't and the Broncos were too good."
