Chasing Adelaide's 5-125, the Heat reached 8-122 in  Saturday night's final at Adelaide Oval.
The Strikers triumphed before 12,379 spectators, the largest crowd ever for a women's cricket game in Adelaide.
The crowd was the second-highest for a WBBL standalone fixture, behind the 15,511 who attended the 2021 final in Perth.
Adelaide join Sydney Thunder, Sydney Sixers and the Heat as winners of two WBBL crowns.
Their latest trophy was collected after a close call in a low-scoring nerve-jangler.
Adelaide's much-vaunted bowlers were miserly - captain Tahlia McGrath (2-16) took wickets with consecutive balls and Megan Schutt claimed 2-30.
The Strikers' star legspinner Amanda-Jade Wellington was superb with 3-16 - she bowled the final over with Brisbane needing 13 runs to win.
The Heat needed 11 from the last three balls and Mikayla Hinkley cracked a six but fell two metres short of victory when caught on the mid-off boundary next ball.
With five required off the final ball, the Heat's Nicola Hancock - who earlier starred with the ball - could muster only a single.
Brisbane's run chase was on a proverbial knife-edge throughout - they were 2-54 after 10 overs.
Adelaide skipper McGrath took wickets on consecutive deliveries in the 13th over, leaving Brisbane wobbling at 4-62.
With five overs remaining the visitors required 45 more runs and Amelia Kerr (30no from 32 balls) coolly steered the Heat through the frantic final overs, only to fall just short.
Earlier, the Strikers batters started brightly before losing momentum - from 2-71 after 10 overs they managed only 54 more runs.
The Heat's Nicola Hancock (3-23) was superb, taking the initial two wickets and collecting another victim late.
Hancock bowled Katie Mack (three) in the second over but the Strikers recovered with an innings-high 66-run stand between Laura Wolvaardt and captain McGrath.
Wolvaardt top-scored with 39 from 33 balls, while McGrath struck six fours and a six in her 38 from 34 deliveries.
The captain's dismissal came at the exact midpoint of the innings and, from then, Adelaide failed to gain any traction.
South African Wolvaardt fell in the 15th over, triggering a slide of 3-13 in an 18-ball span with Heat captain Jess Jonassen (1-19) and Georgia Voll (1-19) also taking wickets.
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