Superstar fullback Walsh registered all three of Brisbane's try assists and then kicked the winning conversion at CommBank Stadium as the Broncos toppled the Panthers on Thursday.
Brisbane have had one of the worst premiership hangovers in recent memory, but with their top-eight hopes hanging by a thread this felt like the game when Michael Maguire's men had a moment of clarity.
With Walsh, Ezra Mam, Adam Reynolds, Payne Haas and Pat Carrigan all back on deck, the Broncos rediscovered some of the steel and fight that took them to last year's premiership.
They were aggressive and stood up to the Panthers in a way rarely seen this year, Haas enjoying a running battle with Liam Henry, and Walsh getting stuck into Panthers back-rower Isaiah Papali'i.
Kotoni Staggs also demolished rival centre Casey McLean and was a big factor in the Panthers centre missing 10 tackles.
"I've seen moments like that for the last couple of months," Maguire said.
"When you get your players out there then they all complement each other.
"Reece got on the back of what was going on in the front row, and there were a lot of special efforts right throughout the team, and people like Reece can come up with a performance like that."
The victory ended a run of eight straight defeats for the Broncos, the second-longest losing streak in the club's history.
This was Penrith's fourth loss all year - their first at CommBank Stadium - and while they will maintain their grip on first spot, a win for the second-placed Warriors on Saturday could cut Penrith's lead at the top to just two points.
Nathan Cleary was also placed on report for a first-half lifting tackle on Mam, who instantly rekindled his chemistry with Reynolds.
Walsh was the true spark the Broncos needed and helped his side take the lead after six minutes when Jordan Riki pounced on a grubber kick sent to the in-goal by his fullback.
Either side of a Brian To'o double, Walsh then sent Kotoni Staggs over on the right.
Cleary missed one of his conversions but added a penalty on halftime to give Penrith a 12-8 lead at the break.
Brisbane dominated territory and had 63 per cent of the second-half possession, but couldn't crack the Penrith defence until the 68th minute.
Walsh hit Josiah Karapani with a cutout ball in the corner to tie up the game, then took the tee from Reynolds, who had missed both earlier conversions.
The Broncos fullback showed no concern under pressure to hit the goal from the sidelines, securing a win to keep Brisbane's paper-thin premiership defence alive.
"I came here knowing it was going to be a high-quality game," Panthers coach Ivan Cleary said.
"I just can't remember a game where I felt like we just ran out of time.
"Reece Walsh was unbelievable tonight and came up with a try that I don't know if many people could stop that one (but) I thought our defence was outstanding."
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