After restricting the Thunder to 7/151, the Strikers looked in firm control at 3/115 before staggering to 9/143 to bring about a sudden end to their season.
The run out of vice-captain Alex Carey (28) via a direct hit from desperate, diving Thunder captain Callum Ferguson proved a pivotal moment, with Rashid Khan and Matt Short duly departing for ducks.
With 34 required off the last three overs, Thunder paceman Chris Tremain sent down four wides in a ragged 18th over which went for 16 before Daniel Sams (3/23), the tournament's leading wicket-taker, swung the momentum back the Thunder's way, sending Michael Neser (12) and Peter Siddle (0) packing.
Jon Wells appeared the Strikers' last hope, but then edged behind on the first ball of the 20th to put the result beyond doubt.
Earlier, captain Travis Head (32) looked fluent before chopping spinner Jonathan Cook (2/16) while Wells was Adelaide’s top scorer with 34.
Player of the Match Alex Hales clubbed five sixes in his electric 59 off 35 balls, his fourth half-century from his past five outings.
In-form seamer Siddle claimed Ferguson (1) LBW and yorked Sams (10) for handy figures of 2/21.
Siddle also ran out Arjun Nair (18) in remarkable fashion due to a ricochet off his heel back onto the stumps at the non-striker's end.
Neser, Rashid Khan, Head and Wes Agar all finished with one wicket apiece.
The Sydney Thunder will now tackle the Melbourne Stars at the MCG on Thursday in ‘The Challenger’ with the winner progressing to the BBL|09 decider against the Sydney Sixers at the SCG next Saturday.