The Emmy-winning actor, whose notable film and TV credits include Mad Men, Us, and The Invisible Man, announced the news on a recent appearance on Jimmy Kimmel Live.
“Are you pregnant or just an incredibly committed method actor?” host Kimmel asked Moss, as she walked out into the studio. “A little bit of both,” she replied.
Moss, who told the talk show host that everything’s “been going really well” so far, asked Kimmel, who has four children with his wife Molly McNearney, whether he had any advice about “things to buy” or bring to the delivery room.
The American comedian and chat show host replied: “Well, buy everything. Buy all the stuff. You’ll get a lot of stuff; everyone who knows you will send you a thing and then you’ll have a lot of them.”
He added that Bill Murray actually gave McNearney “great” pregnancy advice, revealing the comedian’s checklist for supplies to carry to the hospital.
“He said bring Christmas lights to hang, or beads of some kind. A night light,” Kimmel, 56, recalled.
“Because the lighting is terrible in the room,” he continued. “It’s Walmart-style lighting for this blessed event that’s going to happen and you don’t want that.”
Moss did not reveal her due date or the identity of her partner during the interview.
She was previously married to American comedian and Saturday Night Live star Fred Armisen for a little over a year before their divorce was finalised in 2011.
The Handmaid’s Tale was renewed for its sixth and final season in September 2022, ahead of the premiere of the fifth series.
“It has been a true honour to tell the story of Margaret Atwood’s groundbreaking novel and chillingly relevant world, and we are thrilled to bring viewers a sixth and final season of The Handmaid’s Tale,” series creator and showrunner Bruce Miller said in a statement.
Speaking to Kimmel during the episode that was aired on Tuesday night (30 January), Moss said filming for the show’s final season will begin this summer.
She joked it felt like the fifth season was released “37 years ago”, adding fans were starting to get upset about the long gap between the fifth and sixth seasons.
Moss admitted the last season probably won’t be released for another year-and-a-half.
“Have you started blaming this on your child?” Kimmel quipped, before Moss mock-whispered: “I can’t wait to start doing that!”