The album was released on May 18 and sold 135,000 total copies in its first week, including 100,000 traditional album sales. That makes this debut the second-biggest of 2018, just behind Migos' "Culture II", which sold 199,000 copies in its first week.
It's also the first foreign-language album to top the Billboard 200 in over 12 years -- since Il Divo's 2006 album "Ancora."
This marks the second time BTS has appeared in the Billboard Top Ten, the first being their previous album 'Love Yourself: Her,' which opened at No. 7 in 2017.
No other K-pop release has ever broken into the top 10, let alone the No. 1 spot.
Popular K-pop groups like BTS have long had devout fan bases in South Korea and across Asia, but only began breaking into the American market recently.
"Love Yourself: Tear" pushed Post Malone's album "Beerbongs and Bentleys," which had been No. 1 for three straight weeks, to No. 2. BTS also beat out artists like Cardi B, J. Cole, and Playboi Carti.
Some of the group's members took to Twitter to thank fans.
"No. 1 on the Billboard 200.. Thank you so much for letting us see such a good news as soon as we woke up," wrote Kim Seok-jin, better known as Jin, on the BTS Twitter account. "It's amazing and so surreal. Thank you to all who have listened to our music! We will continue to work hard!"
"What a good news from the start of the morning!!! Thank you very much, everyone," tweeted fellow BTS member Jung Ho-seok, known as J-Hope.
South Korea's President Moon Jae-in also congratulated the band on Monday. In a statement, Moon said, "The songs, dance, dreams and enthusiasm of BTS energized and gave strength to young people around the world."
"Their melody and lyrics transcend regional borders, language, culture, and institutions."
Moon finished by thanking BTS for "spreading joy across Korea and the world with your great performances."
K-pop emerged in South Korea in the early 1990s, and labels such as JYP, DSP and YG, built the nation's pop industry from the ground up by creating training schemes that churned out pop stars for music, soap operas and movies.
This accolade is the latest step in BTS' whirlwind rise to success, following their performance at the Billboard Music Awards, where they also won the Top Social Artist award.
The Billboard 200 chart ranks each week's most popular albums in the US. The full list will be posted on Billboard's website on Wednesday, May 30.