As an eventer he represented his country at all grades up to and including World Equestrian Games level, quickly gaining a reputation for his courage and willingness to go all out for the win. It was as a show jumper that Gerry really excelled; participating on 16 winning Nations Cup teams from a total of 43 appearances. He is a winner of 47 international classes, including 9 Grand Prix. In 2007 Gerry was the winner of 4 Grand Prix, including a victory at Dublin CSIO 5*. Gerry Flynn won President Cup with SIEC Comet in June 2008.

Gerry and his winner horse S.I.E.C. Janico had stunning results during 2009 jumping season including 3 victories in Ankara Show- GSGM Cup, Ministery of State Cup and General Stuff Cup. In the last big cup of the season 2009, he placed second with Janico in President Cup (1.45m). He was also the regional Champion of Istanbul among senior riders.