The result has been almost 20 years in the making for the Thunder, which is playing finals for just the second time in its history.
It sets up a bumper grand final against Subiaco on Sunday, with the table-topping Lions well placed after enjoying the week off.
Connor Blakely was dominant in the midfield for Peel, gathering 42 disposals in the 16.13 (109) to 10.10 (70) victory.
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READ NOWLocal product Blair Bell bagged two goals, as did skipper Gerald Ugle, stalwart Rory O’Brien, Shane Yarran and Matt de Boer.
After the match, Ugle said it was a proud moment for himself and the club and he was looking forward to seeing fans get behind the club on Sunday.
“Personally for me it’s an awesome feeling to make it to a grand final; I’ve been fortunate enough to be appointed captain in a strong year when we’ve had a strong side in,” he said.
“The Peel Footy Club is great and hopefully the Mandurah community can embrace us and come down and give us some support next week.
Peel Thunder CEO John Ditchburn issued a rallying cry to Mandurah residents ahead of the biggest game in Peel’s history.
“It’s been a lot of years of hard work for the club for this (moment),” he said.
“We just hope now that the whole town gets behind us; it’s a big week at Domain next week.”
“I heard on the radio the other day that we’ll get 10 people there if we play Subi but let’s hope the town get behind them and we get 10,000 people from Mandurah jump on the train and go.”
What: Peel Thunder’s maiden WAFL Grand Final appearance When: Sunday, September 25, 2.30pm bounce down Where: Subiaco Oval How: Tickets are available online through Ticketmaster or by phoning 136 100. Adults $30. Concession $25. Club members $25. Kids under 15 free.