Though born in Rabat, Kingdom of Morocco, Ronald Agénor is the son of a Haitian Diplomat at the United Nations, Agénor is a former tennis professional who represented Haiti. He is the first and only Haitian player to have earned a top 25 world ranking in singles, reaching No. 22 in 1989.

Agénor learned how to play tennis in 1974 when he was ten. He discovered competitive tennis shortly thereafter in 1978. By 1982, Agénor was ranked No. 8 in the world among juniors. He turned professional in 1983, beginning a tennis career that would span 19 years. He represented Haiti at the Olympics three times during his career: in 1984 at Los Angeles, in 1988 at Seoul, and in 1996 at Atlanta.

Agénor participated several times in Grand Slam singles tournaments during his career, with his first appearances coming in 1988 at Roland Garros and the US Open. In 1989, Agénor reached the quarterfinals of Roland-Garros by defeating Carl Limberger, Tim Mayotte, Claudio Pistolesi, and Sergi Bruguera before losing to eventual champion Michael Chang.

Additionally, Agénor set several records in the tennis field. At Roland-Garros in 1994, Agénor defeated German David Prinosil 14-12 in the fifth set, breaking the record for the longest match in the history of the tournament. In 1987, Agénor faced Yannick Noah in the finals of the Swiss Indoors, marking the first occasion in which two players of color played against each other on in a final on the ATP World Tour. After taking a break from tennis, Agénor returned to the court in 1999 at 35, becoming the oldest player to reach the top 100 since 1991.

Agénor retired in 2002 and then opened the Ronald Agénor Tennis Academy in Los Angeles, California, which still operates to this day.