E! News has learned that the music legend will actually be performing at her son's nuptials—now that's one top-notch wedding singer!
Not only will the groom's mama take center stage during the couple's big night, but her daughter Rhonda Ross Kendrick will be joining her as well.
But Diana won't be the only major icon in the room that night…a source tells us that Stevie Wonder and Smokey Robinson have also been invited to the wedding.
And while the special occasion is bound to be both beautiful and memorable, the 25-year-old dished told E! News that he's more focused on a lifetime with his ladylove.
"Honestly, we could go and get married right now, wherever," he explained while promoting his indie, The Wilderness of James, at SXSW.
"We just want to be married. We're in love. This is the most incredible time I could ever think of in my life and I'm young, but the same time, I've lived a different life than most and I can't think of a happier moment."
Ross, who plays Messalla in the upcoming Hunger Games: Mockingjay, says he knew he wanted to marry Simpson "really quickly."
He gushed, "I was giving it time only because I wanted to give it time, but I would have asked her a month after I was with her."