Olivia Munn showed off her growing baby bump while running errands in Los Angeles.

The "Newsroom" actress and her boyfriend John Mulaney are expecting their first child together. Munn was dressed casually in a black sweatshirt, sweatpants, sandals, and glasses. 

The former "Saturday Night Live" writer confirmed Munn's pregnancy on Tuesday during an appearance on "Late Night with Seth Meyers," declaring that the parents-to-be are "really, really happy." 

Mulaney, 39, gushed about his whirlwind romance to Munn and shared how she's been supportive in his path to recovery after he relapsed on drugs last year and checked into rehab.

JOHN MULANEY CONFIRMS OLIVIA MUNN IS PREGNANT, COUPLE IS EXPECTING FIRST CHILD TOGETHER

"I got into this relationship that's been really beautiful with someone incredible who has dealt with the non-coked-up Bambi version of me and that's been very incredible. She's kind of held my hand through that hell and we are having a baby together," Mulaney announced.

Mulaney revealed that he met Munn, 41, for the first time at Meyers' wedding to Alexi Ashe back in 2013.

Pregnant Olivia Munn was spotted running errands in Beverly Hills.  (Backgrid)

"So it's nice something good came out of the wedding," Mulaney joked. "That's just a clean good joke all around… And [Olivia] got to date me right out of recovery which is what they call a reverse catch. It is a very, very lucky thing to have met this woman."

The comedian also opened up about the months leading up to his relationship with Munn. The pair were first rumored to be dating in May, the same month his rep confirmed he had split from his then-wife, Anna Marie Tendler. Mulaney officially filed for divorce from his former wife of six years in July.

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Mulaney admitted that he "packed a lot" into his life in the last year.

"I went to rehab in September, I got out in October, I moved out of my home from my ex-wife, I host ‘Saturday Night Live’ on Halloween. I relapse on drugs after the show, not directly after. I just mean, well, after goodnights," he said with a laugh.

Munn and boyfriend John Mulaney are expecting their first child. The stand-up comedian confirmed the pregnancy news Tuesday on 'Late Night with Seth Meyers.' (Backgrid)

He said he began to date Munn in the spring after spending time in Los Angeles. While Mulaney was all smiles about his new relationship and becoming a father, he admitted that his road to recovery hasn't necessarily been easy.

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"You knew me before I was on a lot of drugs, you knew me while I was on drugs, you did not know me immediately after stopping drugs so it's been a challenging time," Mulaney told Meyers.

Speaking of his new sober chapter, he said: "It's like newborn Bambi legs. You know how when Bambi's born, Bambi's like, ‘Hey, I used to be on cocaine!'" he joked.

Fox News' Melissa Roberto contributed to this report.