Marsh smacked 79 from 60 balls to become the tournament's top run-scorer as Perth amassed 4-189 a record high score in this summer's Twenty20 series.
The Strikers then crashed to 91 all out in 18.3 overs in a woeful run chase to end their season in front of a sell-out 17,000-strong crowd at Adelaide Oval.
The win enabled Perth to snatch second spot from the Melbourne Stars and book a home semi-final next Wednesday night, while Adelaide's net run rate took such a hit that no result between Brisbane Heat and the Hobart Hurricanes on Saturday night will squeeze them into the semi-finals.
Marsh smashed eight fours and two sixes to top the run-scoring list ahead of Melbourne Renegades skipper Aaron Finch (309 runs), whose team will host a semi-final next Tuesday night.
Marsh and Herschelle Gibbs (54 from 34 balls) built a perfect platform for the Scorchers with a 95-run opening stand from 12.1 overs.
In the process, they took down Adelaide's Test spinner Nathan Lyon, whose only over cost 17 runs and included three consecutive fours to Marsh.
The in-form lefthander was dismissed in the penultimate over as Adam Voges (35 from 18 balls) continued the plundering of Adelaide's bowlers.
The Strikers' run chase was cruelled by early wickets, 2-5 after eight balls with Michael Klinger (0) and Travis Head (4) out.
Tim Ludemann (11), Nathan Reardon (0) and Callum Ferguson (13) soon followed and Adelaide were a hopeless 5-39 in the ninth over, requiring a run rate approaching 13 runs an over to win.
Scorchers paceman Nathan Coulter-Nile dismissed four batsmen yet curiously finished with 3-12.
Coulter-Nile had Kane Richardson, yet to score, out hit wicket but Perth skipper Simon Katich, in unexplained generosity, called the batsman back to the crease.
Richardson finished with 20, the highest score for the Strikers.