Ne-Yo brought all the ladies in his life on a special date night … bringing out all four of his girlfriends to a club where he performed — and, engaging in some PDA on the dance floor.

The rapper surprised the crowd at Slate NY, a popular nightclub in New York City’s Flatiron District … walking through the front door with all four of the women he’s in a relationship with.

After the whole crew pulled up looking ready to party, Ne-Yo hit the stage … playing some of his most well-known songs for the packed crowd.

The star belted out “Sexy Love,” “Miss Independent,” and “Give Me Everything” … before giving the crowd his best a capella “Happy Birthday.”

Later on, Ne-Yo was spotted on the floor … locking lips with one of his GFs — and grabbing a handful of her behind, too.

We’ve talked with Ne-Yo about his polyamorous relationship before … and, he advocated to give polyamorous couples the right to marry — though he admitted matrimony wasn’t for him.

He was walking with two of his GFs at the time … and, while he currently has four, he also told us there’s no cap to the number of partners he’d have at any given time.