Tony Mmoh’s interest in tennis became serious in high school when he won the All-Nigeria High School singles championship three straight years, from 1975 to 1977. Mmoh attended Saint Augustine’s University in Florida from 1978 to 1982 where he competed on the NCAA Division II Falcons tennis team. Mmoh was a Central Intercollegiate Athletic Association (CIAA) singles champion three times and earned All-American honors in 1979 and 1980.

Mmoh’s professional career began in 1978 with an ATP tournament in Lagos, Nigeria. He reached the round of 16 in doubles with partner David Imonitie. In 1985, Mmoh was a singles quarterfinalist at several ATP Challenger tournaments and a doubles quarterfinalist at Geneva, Switzerland with partner Stanislav Birner. In 1986, Mmoh was a runner-up in ATP Challenger singles tournaments at Enugu, Nigeria and Benin City, Nigeria. Mmoh competed in all the Grand Slam tournaments. His best result was in men’s doubles when he reached the round of 16 with partner Nduka Odizor at the Australian Open in 1987. That same year he reached his career-high singles and doubles rankings at No. 105 in October and March respectively.

Mmoh’s last professional appearances were in 1988. That year, he won an ATP Challenger Tour doubles title at Rio de Janeiro, Brazil with partner Bruce Derlin. He also represented Nigeria in the 1988 Seoul Olympics with doubles partner Nduka Odizor. The pair reached the round of 32, ultimately falling to France’s Guy Forget and Henri Leconte.