Tovey revealed on Twitter that he will no longer play werewolf George Sands on the BBC Three show.
"Hey my lovely witty's, you may or may not know by now, but I am leaving Being Human officially," he wrote. "Thought you should all know... Im sorry."
Tovey told The Guardian that members of the Being Human team have long been aware of his decision.
He went on to insist that creator Toby Whithouse would ensure that the supernatural comedy-drama continues to thrive without him.
"With Being Human the story can definitely go on and on," he said. "Toby still runs it and they can do all sorts... add giants and robots."
Aidan Turner (John Mitchell) quit Being Human at the end of this year's series to star in Peter Jackson's The Hobbit.
Damien Molony joined the cast in October as a vampire named Hal.
The fourth series of Being Human is due to air in early 2012.
> 'Being Human' creator teases fourth series