It is the second-straight season a high BBL draft pick has backflipped to play in the tournament after fellow Englishman Liam Livingstone withdrew from appearing for the Melbourne Renegades last year.
Brook, who was selected with pick two in the draft, was set to join the Stars for seven games after England finished their tour of the West Indies in December.
"Naturally we're disappointed that Harry has withdrawn from the BBL but we understand his decision with his increased workload," Melbourne Stars general manager Blair Crouch said.
"We obviously rate Harry extremely highly and we would have loved to have seen him at the MCG alongside Glenn Maxwell and Marcus Stoinis this summer.
"We wish him all the best with his upcoming international commitments.
"Currently the coaching staff and list management team are discussing options for the remainder of the tournament and we look forward to announcing those signings once they have been finalised."
Brook would have missed the first three games of the tournament, anyway, and the Stars had already organised a replacement player for that period.
But they will scramble to find another player to fill the void of Brook, who was a member of England's T20 World Cup-winning side last year.
The Stars continue searching for their maiden BBL title, coming off finishing at the bottom of the table last season.
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