Just three days after celebrating her 36th birthday, Perry whacked 84 not out off 57 balls to lift the Sixers to 5-160 in Friday night's match at Junction Oval.
In reply, Dani Gibson (31 off 20 balls) and Georgia Prestwidge (21no off 13) gave the Stars a great chance to nab victory, with the home side needing 11 runs from the final 10 balls and with four wickets in hand.
That equation became eight runs needed off the final over - with Coyte given the responsibility with the ball.
The nerves were jangling for the Stars when Gibson was caught in the deep, leaving them needing seven runs off four balls.
And even though Coyte missed a chance to run out Kim Garth a short time later, her tight bowling meant the equation became four runs needed off the final ball.
With the game on the line, Prestwidge could only squeeze the final delivery weakly through the on-side for two, with Perry fielding the ball and running it back in to ensure there would be no risk of overthrows.
The result left the Sixers with a perfect 3-0 record, while the Stars are struggling at 1-3.
"It's nice to get on a roll, but the key thing is to keep improving," Perry said.
"Tonight, we played some good cricket, but a few things were rusty in there as well.
"It's really nice to win those close ones, but we've got improvement in us."
For Coyte, her final over marked her second match-winning display at the death this season.
A week earlier, Coyte struck a boundary off the last ball to lift the Sixers to a four-wicket, final-ball victory over the Brisbane Heat.
Coyte's final figures on Friday night didn't jump off the page: 1-27 off three overs.
But her ability to take 1-6 in the clutch final over was huge, leaving the Stars stranded at 7-159 and scratching their heads at the one that got away.
"Sarah Coyte with the ball in hand is really calm and collected at the top of her mark, and she executed perfectly," Sixers pace bowler Lauren Cheatle told Fox Sports.Â
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