For the festive weekend, the pair appeared to be dressed up in coordinated costumes. Karanikolaou, 23, who dressed as Chucky, held Centineo's hand as they walked to a party together. The 24-year-old actor appeared to be dressed up as one of her victims with a bloody slash across his T-shirt.
The outing was their second time celebrating the spooky holiday together.
On Thursday, they both attended a private party with Karanikolaou's best friend, Kylie Jenner, in West Hollywood, according to E! News, which reported that the To All the Boys star was seen kissing the Instagram influencer at the party.
Karanikolaou posted some photos of her costume with some of her pals at the party, but didn't include any images with Centineo.
Centineo was previously linked to Alexis Ren, though the couple split earlier this year. PEOPLE reported in April that the actor and model both unfollowed each other on Instagram and deleted all of their photos together.