Dancing with the Stars judge Inaba was named a permanent panelist on The Talk in early January, and Underwood said she is fitting in "quite nicely."
"She's fun. She doesn't take herself too seriously," Underwood told UPI in a recent phone interview. "She is very open."
Underwood said she connects with Inaba because they are single, while their fellow co-hosts are married with children.
"We both probably want somebody in our lives ... People think in this business: 'Oh, well you have everything. You have it all.' But to be able to talk to somebody that you can relate to ... I think that's a good thing."
The fact that Inaba's arrival dovetailed with Chen's departure made for a bittersweet experience for the 55-year-old Arkansas native.
"I love Julie Chen. This was my first regular TV show job. She really made me feel welcome. We were a great team," Underwood said.
Underwood, who also is a popular radio personality, said she learned a lot about interviewing celebrities from watching Chen set the tone and ask unpredictable questions.
"Nobody gets ambushed on our show," Underwood said. "Not that anybody else does it. I'm just saying that, for us, we're about that conversation. ... We talk, but that also means we've got to listen, so we can intuit what our guests need."
Although she has co-hosted The Talk since 2011, Underwood said it's still thrilling to hear that celebrities such as Lily Tomlin, Jane Fonda, Kobe Bryant, Jamie Lee Curtis and Patti LaBelle will be dropping by.
She also gets starstruck sometimes.
"When you see Tom Selleck walk in, it changes how you feel. He's the kind of guy who will pull a chair out for a woman," Underwood said of the Blue Bloods actor. She said she's also always happy to see actor Shemar Moore.
Underwood said she still travels to perform stand-up shows between 40 and 50 weeks a year.
Describing her act as "very adult," sprinkled with political humor but more "Richard Pryor-esque," Underwood said she feels a sense of responsibility to the brands she represents, namely The Talk and Metamucil, for which she serves as spokeswoman.
"I feel that people trust me. They can relate to me," she said.
Underwood is keenly aware how much the cultural climate has changed in recent years and how that has impacted comedy.
"When I was younger, I was going for the joke. Now I am more in tune with not hurting my audience, and I want to nourish them. Now, would I say some mean-spirited things? Yes, and then I will wait for their reaction," she said.
If the audience hates a joke, she said, she can immediately gauge that and adjust her show accordingly.
Underwood said performing in front of a live audience is an energizing experience unlike any other she has had.
"When those jokes work, when those comments work -- even when they kind of groan -- it's because they're listening," she said.
She is also enjoying her new role as the face of the Metamucil digestive health aid.
"What I like about Metamucil is that it tastes good. I don't think I would do anything that didn't taste good and it's portable and fits my lifestyle."