The Giants finished 16th last year with a 6-16 record, and they were tipped to again struggle in 2023 after losing Tim Taranto, Jacob Hopper, Bobby Hill and Tanner Bruhn during the off-season.
A 3-7 start to the campaign put GWS well and truly on the back foot but a club-record seven-match winning streak - and a clutch final-round win over Carlton - was enough for the Giants to finish seventh with a 13-10 record.
GWS will take on sixth-placed St Kilda in an elimination final at the MCG on Saturday.
The Giants face an uphill battle to win this year's flag, but Himmelberg has full confidence Kingsley's game plan will prove a success during the finals.
"A full new game plan, new coaches - for Kingers to be able to take this team to a finals series in his first year is pretty special," Himmelberg said.
"We're very confident that we can not only participate in the finals but really go deep.
"We're really confident that we've got a style of footy and a game that stacks up in big games.
"Last week (against Carlton) was probably our first final. We had to win to get into finals.
"We put together a performance that was finals-like. We're really confident."
Himmelberg also gave an insight into the way Kingsley has been inspiring the players through his words.
"Throughout the year, Kingers has noted, 'Why not us?'," Himmelberg said.
"That's very much what the playing group's belief is, and the coaches are backing that right up."
The Giants are still hopeful of being able to select forward Toby Bedford after deciding to appeal the AFL Tribunal's decision to uphold his one-match ban for a high shepherd.
The appeal will be heard on Thursday.Â
"We were of the view that it was a footballing act; he was blocking, it wasn't off the ball," Himmelberg said.
All-Australian key defender Sam Taylor (hamstring) is pushing hard to return this week against the Saints.
If Taylor is fit, he's likely to get the job on star St Kilda forward Max King, who kicked four goals when the Saints beat GWS by 12 points in round 10.
"He trained today really well. He'll have main session on Thursday," Himmelberg said of Taylor.
"If he gets through that, I can't see why he's not going to play."
Himmelberg, who signed a six-year contract extension in August, has starred in defence this season.
The 27-year-old's high-flying efforts have earned him two of the three finalist entries for the AFL's mark-of-the-year competition.
