The star hooker, who will return home to play for the new Perth Bears in the NRL after being crowned Wakefield's player of the year, was instrumental in helping Trinity earn a sensational 23-10 win over the Sam Burgess-coached Warrington in the Old Trafford showpiece on Saturday.
And he wasn't the only Australian to shine as Lachlan Walmsley helped set Trinity off to their first title triumph for 58 years when he provided the brilliant reverse pass to send Cam Scott over for the first of their four tries in the 11th minute of a final they largely dominated.
New Zealanders Isaiah Vagana and former NZ Warriors forward Jazz Tevaga went over for scores in their near-perfect 19-0 first half, and despite Warrington's post-break resistance through two Arron Lindop tries, player-of-the match Tom Johnstone powered over, fittingly, for the decider.
It ensured Wakefield, who finished only fourth in the table, completed their astonishing makeover from also-rans to European champions, having only risen from rugby league's second-tier championship to the Super League two seasons ago.
For Smoothy, it also marked the end of an incredible year as he followed up his orchestration of the defeat of mighty Wigan to reach the Manchester showdown with another commanding effort, including a trademark immaculate 40/20 that kept Warrington on the back foot early.
Having come off the bench to help the Broncos to NRL glory over the Storm last year, he was asked how it felt to be only the second man after fellow Aussie, Bradford and Bulldogs centre Ben Harris, back in 2004 and 2005, to achieve the double on either side of the world in successive years.
"Quite surreal at the moment, to be honest," beamed the 27-year-old, who's been given permission to head home to Australia after just a year of his contract, citing compassionate family grounds.
"Just proud of the boys' efforts today. Winning makes it easier, but also harder.
"Easier because you know it's been a successful year and you've pulled a trophy but, yeah, it makes it harder to leave such a close group - and I'm going to miss it."
Wakefield were left already dreaming of a potential crack next season at the World Club Challenge against the winners of Sunday's NRL grand final between the Sydney Roosters and Newcastle Knights.
Wakefield prop Caleb Hamlin-Uele, the younger brother of Cronulla prop Braden, smiled: "We don't know who it'll be yet - hopefully, it'll be the Roosters!"
But Walmsley won't be with them. The NSW-born Scottish international is a free agent and used his brilliant try-assist to tout for his next job on TV.
"Yeah, so I'm looking for a job, if there's anyone needing a winger - a grand final-winning winger!" he told Sky Sports.
However, there was nothing but disappointment for Burgess after another near-miss.
"We're going home disappointed that we lost the physical battle early," said the Rabbitohs great.
