The pair will talk about Keith's new album Graffiti U, his new single Way Too Long and why he loves returning to Australia.
The news of Carrie's replacement comes after the radio host broke down on her last day.
The 37-year-old admitted she's worried about the impact her third child might have on the bond of her older children, Ollie, 11, and Evie, 3.
"I'm very excited about my expanding family," Carrie said on air.
"Ollie thinks we're having a boy and Evie thinks we're having a girl so one of them is going to be very disappointed and one very excited," she added with a chuckle.
She then teared up saying she's been "emotional" thinking about her kids.
"I know families of three and I know they'll all love each other so much, but I don't want anything to happen to their bond. So it makes me a little sad," she said.