Appearing on Zoe Ball's Radio 2 show, the 53-year-old was asked about lockdown life and how her musician star partner helped her. "He did [help]. He actually did," revealed Nicole.
"We were in lockdown, we were in Tennessee in Nashville and the director sent me a text going, 'Would you sing the title track, Dream a Little Dream, for the series?'"
WATCH: Nicole Kidman teases fans with trailer for her new show The Undoing
Elaborating further, she added: "I was like, 'What? No, I so don't want to do that, my voice is not good', which is always my reaction, and she said, 'No, no, I think you can sing it'."
Nicole, who has been married to the Australian country singer since 2006, revealed she started recording inside her husband's studio at their home. "We laid it down and sent it in, and they mixed it so it ended up in the series… I don't know if that's a good or bad thing."
The Others star is currently in Australia with her family while filming the upcoming show, Nine Perfect Strangers. However, her new mini-series The Undoing - which also stars Hugh Grant - will see Nicole take on the role of therapist Grace Fraser, whose perfect life falls apart when a startling accusation is aimed at her husband.
Nicole has been married to Keith Urban since 2006
Meanwhile, in a recent interview published in HELLO! in August, the actress reflected on how the pandemic transformed hers and Keith's lives.
"We travel together, so we are always together, but never where you are in a house and you can't go to the store, to a restaurant of the movies," she said. "Staying home, doing school from home and all of those things that everyone has been doing is a completely different life for us."
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