The septet took home the top three prizes at the 2019 MAMA -- Album of the Year, Artist of the Year and Song of the Year -- winning big at the awards ceremony held at Nagoya Dome.
Six other awards including Best Male Group, Best Dance Performance-Male Group and Best Music Video also went to BTS.
"Year 2019 has been a year of really intense and hard work. Looking back, we had (a time) when we almost gave up, but after some time we can now smile over the past," member Suga said, lifting the Artist of the Year trophy.
"Over the past year, we have grown more and become stronger," he said.
Member J-Hope said in a separate speech after taking the Album of the Year prize that BTS "will try to provide a positive influence and good messages."
Member Jimin hinted at the band's next album, saying, "We are preparing our next album and we might be able to come up with an album that is far better than what you are expecting."
Separately, veteran singer Lee So-ra's 2019 song featuring Suga, "Song Request," was named Best Collaboration during the three-hour awards and performance ceremony.
Girl band TWICE took home Best Dance Performance-Female Group and Best Female Group, while female quartet Mamamoo won Favorite Vocal Performance.
ITZY and Tomorrow X Together lifted Best New Female Artist and Best New Male Artist, respectively.
The 2019 MAMA was well received by fans in Japan despite on-going diplomatic and trade disputes between Seoul and Tokyo stemming from their shared history.
MAMA organizer CJ's choice of Nagoya had raised eyebrows among South Korean fans after the city temporarily suspended the exhibition of a symbolic Korean sculpture during the city's hosting of the Aichi Triennale art festival in the wake of the bilateral rows earlier this year.