Farrell performed in St. Petersburg on Wednesday. John Seine, his agent, said the singer was complaining of breathing problems before and after the show.
Boney M, based in Germany, broke into the charts with "Daddy Cool" and "By the Rivers of Babylon." The latter was No. 1 for five weeks. Boney M had 38 top-10 hits, including 15 number ones in Germany.
Boney M. Was the first Western music group invited by a Soviet leader, Leonid Brezhnev, to perform in the Soviet Union. The group performed in front of 2,700 Russians in Red Square.
Though Farrell headlined the group, he was more a dancer and showman than a singer. The group was put together by German singer and songwriter Frank Farian, who did much of the recorded singing.
The original group of Farrell and three women broke up in 1986 and Farrell continued on his own or with various female back-up singers, maintaining his flamboyant style and glittering costumes. In recent years he toured under the name Bobby Farrell's Boney M, melding disco and Calypso music.
Seine said the cause of death was not known, but Farrell had suffered health problems off-and-on for 10 years. He said he was found dead by hotel staff after he failed to respond to a wake-up call.
The Associated Press contributed to this report