"It did feel very freeing," Jenner said about wearing the swimsuit on Sunday night's episode of I Am Cait. "I did see my reflection in the glass door. Looked pretty good."
Jenner, 65, chose to wear a white, one-shouldered one-piece over an even sexier black bikini selected by Kardashian.
"I love my daughter Kimberly to death, but this is one that she would wear," Jenner joked. "It is probably a little bit more revealing in the cleavage department."
Jenner – who had been reluctant to show her body in a bathing suit – made her debut in front of friends while staying at a secluded luxury villa in Napa Valley, California, dropping a pretty cover-up to step into the pool.
"Putting on a bathing suit represents a lot to me," Jenner said. "It is kind of scary because, you know, you are really exposing yourself."
I Am Cait airs Sunday at 8 p.m. ET on E!