The 33-year-old Skyfall nyota is replacing Sacha Baron Cohen, who left the project earlier this mwaka over "creative differences".
Harry Potter's Daniel Radcliffe had been slated to take over from Cohen but Whishaw emerged as the frontrunner after the surviving members of Queen revealed on The One onyesha in October that he was their juu choice.
Whishaw, best known for his role in Skyfall as Q, has also appeared in TV dramas The saa and Nathan Barley.
He also played Rolling Stone Keith Richards in Stoned, musician Bob Dylan in I'm Not There, and poet John Keats in Bright Star.
Mercury died in 1991 of complications from Aids.
The film will not focus on his final days. Instead, it will focus on the early days of the band, culminating in their headline performance at the Live Aid tamasha in 1985.
Dexter Fletcher, the Lock, Stock and Two Smoking Barrels actor-turned-director, will direct the as-yet untitled project.
