Three more episodes of the Douglas Adams adaptation have been commissioned following a successful pilot last year.
Watkins told CultBox: "I've been doing a series called Dirk Gently, with Stephen Mangan. I'm filming that now; I'm on my way down to Bristol. There's three hour-long episodes and I'm in two of them."
It is currently unclear what role the actor will be playing in the BBC Four series. Watkins previously appeared in the first and third series of Being Human as the vampire Herrick.
He recently starred in Sky1 comedy Trollied, which has been picked up for a second and third series.
Misfits creator Howard Overman will return to write the new Dirk Gently episodes.
> Stephen Mangan 'wants more Dirk Gently'
Watch a clip from the Dirk Gently pilot below: