The couple welcomed their first children, twin babies Moroccan Scott and Monroe, in April.
Talking to US Weekly, the America's Got Talent host said that Carey is "focused" on getting back into shape and dropping pounds she put on before giving birth.
"She's so focused right now on every aspect. She's going to come back and knock out the world. She's getting in shape," he explained.
"At two months, she was walking around in a bathing suit. Every day she's just killing it. I personally think she's going to come out looking better - looking like it's 1990! I think that's what she's aiming for and I think she'll reach that goal."
Cannon recently insisted that his children would not have showbiz careers and hopes that they decide to drive for "something greater than entertainment".