Gomez said she will never forget the birth of the royal child, E! News reported.
"How crazy is that?! I share my birthday with the royal baby, that's crazy!," the Spring Breakers star said
"I'm never going to forget that ever in my life. Everyone's going to say happy birthday to me and I'm going to be like, 'But honestly, it's the royal baby's birthday.' That's what I'm going to say," she added.
Gomez said she was overwhelmed to see the kind of attention the birth attracted.
Kate Middleton and Prince William welcomed their first child at 4:24 p.M., British Summer Time, on Monday.
The child has been named George Alexander Louis.