The stars began dating after meeting on the set of their 2003 movie "Love Don't Cost a Thing", but they split in 2005 after the Cuban beauty discovered Nick had been cheating on her.
They both moved on and subsequently had kids and in 2012, the exes cleared the air in a New York radio interview, during which Nick apologised for his bad behaviour during their failed romance.
It appears the former couple has remained on good terms ever since, and on Tuesday, they headed to Lorna's Jamaican club in Queens, New York with a group of mutual friends.
Christina, who had a short-lived marriage to The-Dream, the father of her six-year-old daughter Violet, has been single since splitting from rapper Lil Wayne last year, while Nick was recently linked to TLC star Rozanda 'Chilli' Thomas.
He separated from wife Mariah Carey in 2014 after six years of marriage. They share five-year-old twins Moroccan and Monroe.