The supermodel model and singer, who were thought to be good friends, sparked rumours of a feud when they both stopped following each other on Instagram recently.
But Naomi, 46, insisted "everything's fine" when she appeared on Watch What Happens Live on Tuesday night.
Host Andy Cohen didn't waste much time before asking the beauty what had happened between them.
"It seems like Naomi Campbell and Rihanna unfollowed each other on Instagram... is everything OK between them?" Andy said, reading out a fan-submitted question.
