Glanville, 45, posted a selfie on Instagram with the 35-year-old singer while celebrating son Jake's 11th birthday.
Rimes married Glanville's ex-husband, Eddie Cibrian, in April 2011 after having an affair with the actor during his marriage to Glanville. Glanville and Rimes were unfriendly for years, but appear to have put their history aside for the party.
"Peace in #calabasturd hanging for Jakes bday," Glanville captioned the photo, adding a heart emoji.
Glanville shares Jake and 14-year-old Mason with Cibrian. She posted a picture with her elder son from the celebration.
"Happy BIRF-Day to me and not this big guy Mason but my other big man Jake," the television personality wrote. "true loves my life time goes so fast enjoy your babies while you can."
Glanville had said in an interview with Watch What Happens Live in March that her relationship with Cibrian and Rimes was in a good place.
"We're great," the star said. "Well, I had to be because I was going to Big Brother. I'm like, 'Can you watch my kids for this long?' Now he's doing a show in Vancouver and now I have the boys."
Glanville is known for starring on the Bravo series The Real Housewives of Beverly Hills.