Rapper RM and singer Jin tested positive on Saturday afternoon, according to Big Hit Music, a day after Suga, another member of the seven-member band, confirmed their infection.
The South Korean group had performed live in Los Angeles at the end of November and then stayed in the United States on vacation, returning on different dates to South Korea.
While RM and Suga are currently asymptomatic, Jin has a moderate fever, the agency noted.
The three infected had the vaccination schedule completed and none were in physical contact with the rest of the group members upon their return, Bit Hit Music added.
Both the United States and South Korea are currently facing a significant increase in COVID cases, as the hyper-infectious variant omicron spreads globally.
BTS reached world stardom with their single “Dynamite,” which reached the top spot on the Billboard Hot 100, making them the first South Korean group to top the famous American music chart.