According to SFX, the Sherlock star will play Gary Mitchell, an original series character who attended Starfleet Academy with James Kirk (Chris Pine).
Mitchell and Kirk were friends until an encounter with a galactic barrier transformed him into a cruel, ruthless and supremely powerful villain.
The actor was cast in JJ Abrams's sequel earlier this year, but there has so far been no confirmation of what part he is playing beyond the fact that his character is a villain.
Watch Simon Pegg discussing Star Trek 2 with Digital Spy below:
Karl Urban, who plays Bones in Abrams's rebooted franchise, appeared to unintentionally confirm the role, saying of Cumberbatch: "He's awesome, he's a great addition, and I think his Gary Mitchell is going to be exemplary."
Rumours that Cumberbatch would be playing legendary villain Khan have been denied by his co-star Simon Pegg.
Pine has recently praised Cumberbatch, describing him as "fascinating", while Damon Lindelof has called his performance "iconic".
Photo gallery - Star Trek 2 on-set pictures: