The surprise moment came after the pair performed their new single "Olvídame y Pega la Vuelta" together which was followed by Lopez presenting her ex-husband with the Person of the Year Award.
"Marc is a living legend. He is a magical and pure artist giving away classics that will stay forever. He will always be many things in my life," the pop star said on stage when translated from Spanish.
"He will always be a lot of things to me. He's my kindred spirit. My love."
As those in attendance started to chant "beso" meaning kiss in Spanish, the two then locked lips during a tender moment. The scene was shared by the Latin Grammys on Twitter.
Lopez and Anthony split in 2011 after seven years together and finalized their divorce in 2014. They share 8-year-old twins, Emme and Max together.
In October, the duo made headlines again when it was announced that Anthony's company Magnus Media would be helping Lopez develop and executive produce an upcoming Spanish-language album.