The 34-year-old was shifted to fullback to replace star Kayln Ponga, and terrorised the Raiders' right edge, inspiring tries and leading their swift ball movement at a wet GIO Stadium on Sunday.
It meant the first half was a see-sawing contest, with the scores locked at 18-all at the break, before the ladder-leading Canberra pulled away to win 44-18.
"You look at Dane Gagai and he'd be the first player I would re-sign," Stuart told reporters after the game.
"He was by far the hungriest, best player out there tonight. He just never stopped trying. That builds teams."
Gagai was dropped from his centre position in the Queensland State of Origin team this season and replaced with Roosters bolter Robert Toia and playmaker Hamiso Tabuai-Fidow.
The pairing was Queensland's most inexperienced but made an impact, meaning Gagai did not gain a recall.Â
While he shone in the first half against Canberra, Gagai was unable to reignite Newcastle in the second half as the Green Machine scored five unanswered tries, didn't let up on errors and delivered a solid defensive display.
The Knights' season is now all but over as they sit well adrift of the top eight, tied on 16 points with last-placed South Sydney and without stars Ponga, Bradman Best and Fletcher Sharpe.
But for the Raiders, they now sit two points clear in the minor premiership race with six rounds left before the finals.
Canberra don't have to play any current top four opponents in the run home, and have a bye in hand.
If they win the minor premiership, it would be their first since 1990, when Stuart was halfback.
The victory was also the Raiders' ninth on the trot - the first time they have achieved that feat since 1994.
Matt Timoko starred for Canberra, weaving and winding through Newcastle's defence and earning two tries.
Joe Tapine (139m) led the Raiders up the middle, with Jamal Fogarty providing circling kicks and two try assists.
After a try-for-try first half, the Knights looked energised and ready for more points.
But when they were defending on their line seven minutes in, Tom Starling strode through the centre of their defence.
Newcastle stopped in their tracks and raised their arms complaining of an obstruction.
But the bunker overruled it, giving Canberra the first of their seven tries.
Knights coach, Adam O'Brien said he agreed with the bunker's controversial decision.
"I reckon we stopped. Phoenix should have kept moving," he said.
"That deflated us a bit, and we've got to be able to overcome that. We have to own it.
"I thought in the first half not everything went to plan but we showed a heap of resolve."
Substitute Noah Martin was also able to score his first NRL try when he pounced on a Jamal Fogarty kick.
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