On their home court at the Perth Arena, the Wildcats avenged the hurt of the past two seasons – in which they lost both grand finals to the New Zealand Breakers – with a stellar defensive display.
While Adelaide squared the series at 1-1 on Friday, Perth had a 3-0 home record against their opponents this season.
And they extended that to four with a thumping 34-point win that was set up in the second quarter.
The Wildcats led just 18-15 at the first change but blew their opponents out of the water with a 29-14 second period.
They never looked back from there, as Shawn Redhage (16 points) and grand final MVP Jermaine Beal (15 points) played starring roles.
Damian Martin (14 points, six rebounds) and Greg Hire (nine points, nine rebounds, five assists) were also excellent for Perth, who continued to extend their lead throughout the match.
Only Anthony Petrie scored in double figures for the losers, with his 20-point haul a rare highlight for Joey Wright's men.
Adelaide made just 22 of 73 shots during the game as Perth's outstanding defensive effort ensured the title would go to the Wildcats.
And captain Martin was delighted to erase the memories of Perth's previous play-off heartbreak.
"It's indescribable," Martin told the NBL's official website.
"After losing the last two, to finally be on the other end and holding up that trophy is a dream come true.
"And we couldn't have scripted it any better at home in game three in front of 14,000 people."
Perth coach Trevor Gleeson was similarly elated with his side's defensive effort.
"The guys defensively got on a roll," Gleeson said.
"This team defensively has the ability to lock teams down and we locked Adelaide down in the second quarter. We got on top of them and built the pressure and we did that again in the third.
"The guys stepped up and really executed the game plan and I am so happy for them."
Adelaide coach Wright was still proud of his side, despite the heavy defeat.
"I am happy with our guys for fighting through what they fought through…I'm proud of what they've done this year," he said.
"I think we got the best out of ourselves this year and hopefully we can try and get better next year."