The Bleeding Love hitmaker took her relative to a showbiz bash, but Lewis began to regret her choice of guest when her aunt began hounding the Hollywood actor.
She tells Britain's Celebs on Sunday magazine, "I took my auntie to an event and she stalked Will Smith saying, 'I'm going to get a picture of you with him'. I was like, 'Please don't embarrass me!'
"But she marched up and dragged him over to me and said, 'You need to have a picture with my niece Leona, she's a singer'. And he was really sweet to her and like, 'Ok, Auntie!' even though she was being a crazy person. He's used to it I imagine, but he knew who I was so that was kind of cool."