Gwen Stefani loves to dress up — especially when there's a good costume involved.

The pop star got a head start on Halloween when she, boyfriend Blake Shelton and her three sons with ex-husband Gavin Rossdale attended her niece Stella Stefani's 9th birthday party — which happened to be a holiday-themed costume party — on Oct. 20.
Gwen, who was dressed up as Sally from "The Nightmare Before Christmas" in Disney Halloween's Sally Skellington Costume for Adults, posted a ton of photos and videos on her Instagram Story from the bash, including a sweet clip of herself kissing Blake, who came dressed as a sailor (and later showed off his dancing skills).

The pop star also shared pics of son Kingston, 12 (who was dressed as a pirate), with uncle Todd Stefani (who was dressed as Han Solo). Gwen's middle son, Zuma, 10, was dressed in a SpongeBob SquarePants costume while youngest son Apollo, 4, ran around in werewolf garb.

Gwen also posed for some pics with Todd's other half, Jennifer Stefani, who hosted the bash dressed as Princess Leia.

During the backyard b-day party, the kids played limbo, busted open a ghost-shaped piñata, played games and listened to live accordion music while grandparents Dennis and Patti Stefani — who were dressed as a couple of jack-o-lanterns — helped out.

Gwen also posed for a pic with birthday girl Stella, who's modeled for her kids clothing line and is incredibly close to her boys.

We can't wait to see how Gwen, her family and Blake dress up on Oct. 31!