J.Lo, 42, showed off her famous curves in a bright yellow bikini as she watched her children play in the water.
She was then snapped jumping into the pool where she was joined by her four-year-old daughter, who looked super-cute in a red, frilly two-piece.
Jennifer and Caspar, 25, have been dating for about a year, after she split from Marc Anthony, her husband of seven years, last July.
It seems that her children get on well with her new man - Emme was all smiles as she balanced on his shoulders and played in the pool, and both children looked happy and confident in the water.
J.Lo arrived in Miami yesterday in advance of the last two performances of her world tour with Enrique Iglesias.