The pair are friends and were team-mates at American Top Team Gym before Nunes left in 2022.
Nunes, 38, is widely regarded as one of the greatest MMA fighters of all time and is returning to the sport after retiring in 2023.
She is a former featherweight and bantamweight champion and the only woman in history to hold two UFC titles in two weight classes simultaneously.
Harrison is a two-time former PFL champion before claiming UFC gold in only her third fight in the promotion last year.
She says the prospect of competing against Nunes was a driving factor behind her successful recovery.
“Mentally, to go from that high and that low is hard, and when I was finally able to get back on the mat, I really struggled with confidence,” said Harrison.
“I think I was so scared to hurt my neck again, number one. That lack of confidence made me question if I was ever gonna feel like me again.
“So, I had a lot of soul-searching to do. If I was just being a mum, I could be fine. But getting back to the Kayla that I was, was really hard. It’s been hard, but it’s been worth it.”
Harrison has won 19 of her 20 fights since her MMA debut in 2018, with her only defeat coming against Larissa Pacheco in 2022.
After questioning her future in the sport over the past 12 months, Harrison did not confirm if the fight with Nunes would be her last.
“We’ll cross that bridge when we get to it,” added Harrison.
“We’ll see. I’m really grateful to be back doing what I love again against the greatest of all time, and I can’t wait.”