The Bears entered the game only having lost to undefeated Echuca this season and with 56 and 61-point wins against Mooroopna, but the Cats produced an almost unthinkable turnaround in winning through to the decider by 28 points.
The NCWL will find a first-time winner, with the Cats to take on Echuca at the Goulburn Valley's home of football - Deakin Reserve - for Sunday's grand final.
After doing what many thought was impossible, Cats coach Terry Mahoney could not have been more proud of his history-making side.
"Everyone was absolutely thrilled; it's a real bonus we've been able to get that reward of playing finals and to get that extra thrill of getting through to the grand final - we couldn't be happier," he said.
"I'm extremely proud, we went into the weekend hoping for the best, but realistically it felt like it could be our final game of the season and we were prepared for that.
"I thought I'd end the day telling the girls how proud I was with them for the season, but then you're thinking 'gee, hang on a minute, we might be able to win this'.
"Suddenly, after the game you're talking about the build-up to a grand final."
From the jump, the unlikely result seemed a chance; an outside one when Mooroopna kicked the only 10 points of the first quarter, but the alarm bells were well and truly ringing when the Cats kicked three goals to Shepparton's one in the second quarter to hit half-time 20 points ahead.
The Bears' brilliant season was on the line, but away from home in heavy conditions, they could not find an answer, the Cats kicking the only two goals of the third term to wrestle a game-winning 36-point break.
Having held on to win by 28 points, Mahoney said the side had played with freedom with the pressure firmly on the reigning premier.
"You can't take anything away from Shepparton or Echuca, they've clearly been the best two sides this season and the most consistent," he said.
"Obviously we knew it was going to be a big challenge, but we went in with nothing to lose, we'd already achieved more than we thought we would this season. We played the ball on its merits, got some momentum early and were able to carry that through.
"Shepparton had only dropped two games this season and this weekend we'll play Echuca that hasn't dropped any. From our perspective, we just go out there and play footy, we had a relaxed build-up and embraced the moments with your friends and teammates."
The biggest win in club history took huge performances from the entire side, but midfield maestros Kayla Shepherd and Tamara Smith led the way along with captain Kristen Atkinson.
Thamar Atkinson presented well and rucked hard, while Britt Tancred and Kiara Cooper found three goals between them, and applied elite defensive pressure to stop the Shepparton run.
For the Bears, Samantha Heron kicked the side's only two goals, with Ilmie Cuthbert, Ashlee Thorneycroft and Emily McClure standing out.
Now one formidable challenge stands between the Cats and premiership glory; Mahoney's message was simply to enjoy an experience many have dreamed of having.
"We're proud whatever happens, and we want the girls to soak it right up," he said.
"It's about enjoying it because the opportunity to play in a grand final doesn't come around too often. We're really proud of the girls and we want to make sure they're proud of themselves.
"We approach it exactly the same, we respect them very highly, it's a team that's been building for two or three years. They're very well coached, a phenomenal running team, it will take all of our best efforts to compete with them.
"But it's the same attitude, we've got nothing to lose, we expect they will be pretty confident."
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