Greg Allen joined the RTÉ Radio sports department in 1984 as a presenter and reporter.

By 1987, Greg Allen had begun reporting on athletics and went to the Seoul Olympics in 1988 as athletics reporter and interviewer. That began an involvement with athletics which continues today. Since then he has covered five Olympic Games as radio athletics commentator. He has also covered every World Athletics Championship since 1993 and each European Athletics championship since 1990.

In 1991, Greg Allen began covering golf for RTÉ. Since then he has commentated on the Ryder Cups, British Opens, Masters' Tournaments and US Opens and hundreds of other tournaments both nationally and internationally.