The This Is England star, who debuted in the E4 drama's third run as Rudy, told CultBox that the new episodes will have a "fresh outlook".
"I'm really looking forward to it, and I'm also mildly terrified of it, 'cos there's a lot of work involved, but it's such a good laugh when you're doing it," he explained.
Misfits will introduce three new regular characters, following the departures of Iwan Rheon (Simon) and Antonia Thomas (Alisha).
"I'm looking forward to [the next series] 'cos there's going to be some new characters and I think that's a really good thing," said Gilgun. "[It'll give the show] a fresh outlook."
Misfits was officially picked up for a fourth year in December.
The series will return to E4 in late 2012.
> Misfits star will not return for series four
> Misfits: Second star confirms show exit
Watch the Misfits cast discuss the last series below: