The singer, 44, and comic actor, 50, “are seeing each other and very into it,” a source tells Us Weekly, adding that the romance started up four months ago.

The Tower Heist star — who has eight kids from previous relationships — even cheered on the mother of two (who’s been separated from singer Keri Lewis since 2009), backstage at her Feb. 19 L.A. concert.

While Braxton’s rep insists “Toni and Eddie are just friends and have been fans of each other’s work for a long time,” the insider says, “Their kids have met and everything. It’s getting very serious.”

In addition to first wife Nicole Mitchell, Murphy dated former Spice Girl Melanie Brown from 2006 to 2007, and exchanged marital vows with Tracey Edmonds in 2008 in a “symbolic” ceremony that was never made legal. Back in the late 1980s, Murphy was linked to another big-voiced R&B superstar: the late Whitney Houston.

Braxton’s search for love after her split from Lewis was a major plot point in the most recent season of her reality show Braxton Family Values.