The No Doubt singer, 49, was in an elaborate costume as Sally from the 1993 animated Tim Burton film The Nightmare Before Christmas, while the country star, 42, wore a sailor outfit and jeans at the Stefani family celebration for her niece Stella, whose dad is Stefani’s brother Todd.
Stefani’s three children with ex-husband Gavin Rossdale were also in attendance, with Kingston, 12, in a Star Wars outfit complete with lightsaber, Zuma, 10, as SpongeBob SquarePants, and Apollo, 4, as a wolfman with a scary mask.
The party featured a huge candy-filled ghost piñata, which Apollo took turns trying to hit, as well as a limbo competition. Food at the celebration included cupcakes decorated with spiders, pumpkins and bats, while an accordion player provided music.
Shelton, who was spotted doing a funky dance in one of the clips his girlfriend posted to Instagram, fooled around with fake ghoulish fingers at the celebration, jokingly picking his nose for the camera.
“That was a good party,” the singer told her brother in a video on her Instagram Story at the end of the night. “We came, we saw, we did it,” he replied, giving a thumbs-up.
Scroll down to see the fun pics.