The "Bad Guy" hitmaker is such a superfan of the TV comedy that the producers of podcast series "An Oral History of The Office" created a special finale all about her love of the programme, titled "Beauty in Ordinary Things... - The Legacy of The Office (2013-Present)".
"The Office" stars and revolving podcast hosts, Brian Baumgartner and Steve Carell, sat down with their famous superfan days after she scooped six Grammy Awards in February, and she was so stoked she offered to give them one of her trophies.
"I don't need all of them, you can have one," she giggled.
But "The Office" is serious business for Eilish, who revealed that tuning in "takes me away from the reality of my life," adding, "It's a safe space."
She also confessed to watching the entire U.S. version of the show, which aired from 2005 to 2013, 14 times, often on her iPhone, adding it's not a new obsession.
"Honestly, because I've been getting older, every time I watch it I understand something new, because I started at (age) 12," the 18-year-old adds. "Most of the things that I know are because of 'The Office'. I swear to God."
Billie's mum Maggie even popped up on the FaceTime call to confirm that her daughter watches "The Office" "day and night," while series stars Jenna Fischer and John Krasinski also dropped by to share some of their favourite memories.
The final episode of "An Oral History of The Office" drops on 15 September.