Jackson shared photos of the new ink on her Instagram story Saturday as the pair were seen smiling together after visiting Tattoo Mania in West Hollywood, Us Weekly reported.
The tattoo is located on Jackson and Culkin's arms and resembles a spoon.
This is the latest reunion between Jackson and Culkin after the duo was featured on Jackson's Instagram in April. The post featured Cullkin resting on a sitting Jackson who was sporting pink bunny ears. In December, Jackson was seen on the photo sharing app painting Culkin's toenails.
Culkin is also godfather to Jackson's brothers, 20-year-old Prince Jackson and 15-year-old Blanket Jackson. Culkin was close friends with their father leading up to his death in 2009.
Jackson last made headlines in June when she honored Michael on the 8th anniversary of his death. "My angel, my king, my universe. 8 years without feels like a lifetime," she wrote alongside a fan-altered photo of herself with her dad.