The New Zealander was riding his horse The Drover at the Somerford Park Horse Trials on Sunday afternoon when he suffered a fatal fall.
The horse was not hurt in the incident, which took place on fence 4B of the cross country course.
"This is a tragic day for our sport and thoughts of everyone in the NZ equestrian community are with the rider’s family at this terrible time," said Equestrian Sports New Zealand chief executive Jim Ellis.
"Tom was a talented showjumper and eventer who was in Europe to fulfill his dream of competing as a professional event rider - a dream he achieved but which has been tragically cut short."
Hundreds of tributes to Tom have been paid on social media sites, with friends describing him as, "funny, caring and magic to be around… an awesome guy."
Tom had been based in Cambridgeshire since 2012 when, and after several years competing at grand prix level in showjumping, he decided to focus on eventing.
Ellis added that he had "undoubted potential" and had high hopes of representing his country at Olympic or World Championship level.
"For riders to get to the top all the pieces of the jigsaw have to fall in place but he was at the right place."