Eight-part series Becoming Human continues the story of vampire Adam (Craig Roberts) as he attends college and meets werewolf Christa (Leila Mimmack) and the ghostly Matt (Josh Brown).
The entire run will now be transmitted as a 50-minute compilation special on Sunday, March 20, a week after the third series of Being Human concludes its run.
"We were delighted when Becoming Human found such a loyal and enthusiastic audience online," said creator Toby Whithouse. "The reaction was beyond our most optimistic dreams. And so for the BBC to give us this opportunity to share the show with a wider audience is fantastic news."
Craig Roberts previously told DS that he is "definitely" interested in filming a potential second series of the spinoff.
The third run of parent series Being Human will conclude this Sunday at 9pm.