The pair arrived hand in hand at a conference in Pasadena California, and looked perfectly at ease as they posed for photographers with their arms around one another.
J-Lo, 43, even told reporters that she and Marc "have a great time working together".
The former couple, who are parents to twins Max and Emme, split last summer and have both moved on with their lives.
Jennifer is dating her handsome backing dancer Casper Smart, and recently took the 24-year-old on holiday to Mexico with her children.
Meanwhile 43-year-old Marc found love again with model Shannon De Lima, who is also 24.
Their new romances are clearly doing wonders for the former husband and wife, who were glowing with health and happiness.
J-Lo was on bombshell form in a blue leather dress and nude stiletto heels.