The record, which sees Gaga return to the rocket-powered pop of her debut, sold 53,000 copies, the biggest opening week of the year so far.
It is also the star's fastest-selling album since 2013's Artpop.
The album follows Gaga's performance in A Star Is Born, for which she won an Oscar for best song in 2019.
Critics have called the record a return to form, after the country-leaning acoustics of her fifth album Joanne and the misfiring experiments of her Artpop project.
"Song for song, it's her best yet," wrote Variety magazine, adding: "She sounds like she knows exactly who she is, what she wants to say and how she wants to say it."
"Her pop renaissance couldn't come at a better time," agreed Rolling Stone, while The Independent praised the star's "anthems of self-doubt, self-reflection, self-destruction and self-reclamation".
Gaga, who has suffered with chronic illness and depression, said the record was intended to be an antidote to hard times.
"I'm making a dance record again and this dance floor… it's mine, I earned it, and all that stuff that I went through," she told Zane Lowe in a recent interview.
"The beginning of the album really symbolises, for me, what I would call the beginning of my journey to healing," she added, "and what I would hope would be an inspiration for people that are in need of healing through happiness, through dance."