On Broadway, she sang about losing her head. Now, in her Upper West Side apartment, she’s singing her head off.

Welcome to “Karaoke and Chill,” Andrea Macasaet’s two-week, self-recorded marathon. Born of frustration and boredom, it began as a way to connect with her family.

“Karaoke was always big in my Filipino household,” she tells The Post, “so I thought, I’m gonna sing a couple of karaoke tracks and sent them to my mom, a protective little Filipino lady who wants her baby home.”

“Home” is Winnipeg, Manitoba in Canada, which Macasaet left to star in “Six,” a rollicking show about the many unhappy wives of Henry VIII. It was a hit in London, and Macasaet was all set to make her Broadway debut in it on March 12 — the night Broadway went dark.

Restless after a week of self-isolation, she started her quarantine series in her bedroom: 14 straight days of karaoke she shared with her family and her 14,000-plus Instagram followers.

Andrea Macasaet
Andrea MacasaetAndrea Macasaet

“I advertised it as ‘I karaoke, you chill,’ ” says Macasaet (@andrea.cesyl), who plays a karaoke track on her iPad, streams it through her wireless headset and then records it on her iPhone. Unlike the elaborate costume she wears onstage, she records herself in sweatpants and a hoodie or tee or anything comfy.

And yes, she says, she’s taken requests. Along with “Don’t Lose Your Head,” her signature song in “Six,” she’s had several calls for numbers from other shows: “When He Sees Me” from “Waitress” (“I’ve always loved that musical”) and “I’d Rather Be Me” from “Mean Girls.” That last one features the presciently pandemic sentiment, “The world doesn’t end. It just feels it does.”

But her playlist wasn’t limited to Broadway.

Andrea Macasaet (second from left) in "Six."
Andrea Macasaet (second from left) in “Six.”Joan Marcus

“One of my friends typed in ‘Tennessee Whiskey/Chris Stapleton,’ ” she says. “I knew that song, but never touched country, so that took me a couple of days to learn. I wanted to do it justice.”

For now, 14 videos later, she’s decided to chill a bit herself, her goals accomplished.

“It’s connected me with a lot of friends I haven’t spoken to for a while, and got me to catch up and make new friends, too,” says Macasaet, who can’t wait till Broadway reopens.

“I can just imagine what it’s going to feel and look like when it does, and when ‘Six’ actually has an opening night,” she says. “How epic that will feel?”