Kris Jenner admitted the "biggest mistake" in her life was being unfaithful to her ex-husband.

The reality star candidly spoke out about her infidelity that occurred while she was married to Robert Kardashian, Sr. for 12 years. 

"What was your mindset when you cheated?" Khloe Kardashian asked her mother on Thursday's episode of "The Kardashians" on Hulu.

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kris jenner and robert kardashian sr

Kris Jenner confessed cheating on ex-husband Robert Kardashian was "my life's biggest regret." (Getty Images)

"When you did that with my dad, and you had four kids and you had a family? … Yes, I know you were really young...."

Jenner was at first startled by the question, but then replied, "…being really young and dumb is something that plays into it because you don’t really understand the consequences of your actions."

Kardashian dug into the conversation deeper and asked, "But what was my dad not doing that made you want to look elsewhere?"

Kris Jenner, Kourtney Kardashian, Kourtney Kardashian and Kim Kardashian

Kris Jenner was married to Robert Kardashian Sr. from July 1978 to March 1991. The couple had four children together: Kourtney, Kim, Khloe and Robert Kardashian Jr. (Jon Kopaloff)

The mom-of-six confessed, "I don't know because he was such a great husband and such a great dad… I think that I fell into a situation where I thought that the grass was greener somewhere else, and I made a huge mistake. That’s my life’s biggest regret."

Jenner was married to Robert Kardashian from July 1978 to March 1991. The couple had four children together: Kourtney, Kim, Khloe and Robert Kardashian Jr. 

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Kris and caitlyn Jenner

Kris Jenner found love again after her marriage to Robert Kardashian, Sr. (Araya Doheny/Getty Images)

The businesswoman and "mom-ager" then married Caitlyn Jenner and the pair welcomed two children — Kylie and Kendall Jenner. They announced their separation in October 2013.

Jenner continued to open up about her marriage with her ex-husband Kardashian. 

"I’m not proud of the way I behaved during that time… Everything happens for a reason. I really do live my life by thinking God has a plan and without that whole thing happening there never would’ve been Kendall and Kylie," Jenner pointed out. 

Robert Kardashian Sr., O.J. Simpson

This May 1995 file photo shows murder defendant O.J. Simpson, right, consulting with Robert Kardashian and Alvin Michelson, left, during a hearing in Los Angeles. (Getty Images)

Kardashian died at age 59 on Sept. 30, 2003, less than eight weeks after he was diagnosed with esophageal cancer. He was lauded as a stout member of O.J. Simpson’s legal defense "dream team" after the former football star was charged with murdering his ex-wife Nicole Brown and her friend Ron Goldman in June 1994. Simpson was acquitted after what many still consider the "trial of the century."

Robert Kardashian Sr., O.J. Simpson

Murder defendant O.J. Simpson, right, listens to testimony by the Los Angeles County Coroner. Robert Kardashian sits next to him. (Getty Images)

Jenner is currently dating Corey Gamble, 42, and the couple have been public with their relationship since 2015, shortly after she divorced Caitlyn Jenner. Gamble was previously Justin Bieber's tour manager.

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The conversation about Kris cheating on her ex-husband was brought up as Khloe sought advice on her own tumultuous relationship. 

KHLOE KARDASHIAN WAS SECRETLY ENGAGED TO TRISTAN THOMPSON WHEN HE GOT ANOTHER WOMAN PREGNANT: REPORT

The 39-year-old was previously in a relationship with NBA star Tristan Thompson before she discovered he had fathered a child with Maralee Nichols while the pair were engaged. 

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Thompson and Kardashian share two young children: daughter True, 5, and a son, Tatum, whom they welcomed via surrogate in August 2022.