Ampon made a good start of his career in the Far Eastern Games, winning the tennis singles gold medal in the 1934 edition.

[5][6] Ampon participated in the 1950 Pan American Tennis Championships in Mexico City and won the singles event, his finest career title.

[8] In 1952, Ampon made it to the quarter-finals of the French Open at Roland Garros but narrowly lost to world number one Frank Sedgman (AUS) he reached the final of the Scottish Championships losing to Ian Ayre.

[9] The same year Ampon lost an all-Filipino final in Oslo, Norway, to Reymundo Deyro, arguably his greatest rival and partner in Philippine tennis history.

In the Davis Cup he went on to lead the country in the Eastern Zone for more than a decade and made a prolific partnerships with other Filipino tennis legends Raymundo Deyro, Johnny Jose and Cesar Carmona.