Shane Yarran bagged three goals for the home side, while ball-magnet Matt de Boer continued to press his case for a contract extension at the Dockers, gathering 31 disposals and laying a game-high 10 tackles.
With 17 Fremantle-listed players in the line-up, Peel went into the do-or-die final as favourites and it showed early as they seized control of the match, keeping the Royals goalless in the first term to lead by 28 points at the first change.
East Perth muscled theirway back into the contest in the second term as they kicked with a helpful breeze.
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READ NOWHowever, Peel recovered late to maintain the advantage at the main change.
The third term belonged to the visitors, something that would have concerned Peel coach Cam Shepherd, just two weeks after his side faded away in the final term to go down to then rivals Subiaco.
But the Thunder held firm, keeping the Royals goalless in the final term before piling on four unanswered goals to post the 12.14 (86) to 5.7 (37) win.
The maiden finals win was soured by an injury to the luckless Anthony Morabito in the first term.
Morabito, a former number four draft pick, has endured a torrid time with injury – with the latest setback threatening to curtail his AFL career. Out of contract at season’s end, the 24-year-old would have been hoping to impress Fremantle coach Ross Lyon who was in attendance.
Zac Clarke dominated the ruck as he fights for his AFL career, while Alex Silvagni may figure in the votes as he finished with 11 marks in defence, keeping the Royals at bay on a number of occasions. Connor Blakely (25 disposals) and Rory O’Brien (23 disposals) also would have caught the eye.
Peel Thunder also earnt the respect of the East Perth faithful as they formed a guard of honour for Royal’s stalwarts Craig Wulff and Paul Johnson as they were chaired off for the final time.
Next Sunday Peel face West Perth at Arena Joondalup for a spot in the grand final, with bounce down scheduled for 2.10pm.
The Thunder are yet to beat West Perth this year.