The "Hero" hitmaker wanted her four-year-old twins, Moroccan and Monroe, to enjoy the spooky holiday on Saturday, so rented a USD 15 million estate near Beverly Hills from Airbnb and threw a party, reported E! Online.
"Mariah and Nick got along great and were super friendly towards one another," a source said.
Guests, including Tracey Edmonds and Jeff Beacher, tucked into candy apple martinis and Sugar Factory candy as they danced the night away, while there was also tasty treats such as fried mac and cheese for the children in attendance.
Ahead of the party, Moroccan and Monroe donned Batman and Batgirl outfits and posed for photos with their parents before going trick or treating at neighbouring homes.
Cannon, who dressed as a zombie, shared a picture on social media, writing, "#RocandRoe going hard this Halloween! #BatGirl #Batman. And Batman escapes with a sack full of candy!! (sic)"
It was previously claimed the "America's Got Talent" host is very supportive of his ex-wife's new romance.