Trainer Joseph O'Brien and champion jockey Nina Carberry were among those who attended the removal of jockey JT McNamara.
Mourners filled the small church in Manister, Co Limerick, which is surrounded by fields owned by the powerful Qatar Racing.
The removal was delayed because of the number of people from the horse racing community who came to express their sympathies to the renowned jockey's wife Caroline and their young children, Dylan, Olivia and Harry.
Several mourners had travelled from the Galway Races, while others had come over from England.
JT (41) was paralysed in a fall at Cheltenham three years ago and had suffered ill-health since, with frequent admissions to hospital.
President Michael D Higgins and Taoiseach Enda Kenny will be represented by their aides-de-camp at the funeral today, while Mr Kenny personally rang Mrs McNamara to express his sympathies.
Racehorse owner JP McManus and former jockey AP McCoy visited the family home earlier.
Celebrant Canon Gary Bluett described JT as a man who had been a beacon for his sport and said racing had been the passion of his life.
"He was a hero to many, many people," he said. "JT was a strong character and outspoken."
He added that he had suffered greatly since the horrific accident, spending much time in hospital.
"But he never gave up," he said.
JT died at his home in Croom, Co Limerick, on Tuesday, surrounded by his family.
He had battled bravely after suffering the devastating injury in 2013 that left him paralysed from the neck down.
After intensive treatment in Ireland and the UK, he eventually returned home in June 2014, determined to carry on working as a trainer from his wheelchair.
As the world of horse racing mourned a much-loved son, tributes to the record-breaking amateur jockey have been flowing from some of the greats in the sport.
Among them was renowned trainer and pundit Ted Walsh, who said JT was "admired, liked and respected by everybody in the racing industry".
Trainer Michael 'Mouse' Morris described him as "a pure gent, a brilliant horseman, a smashing gentleman and a lovely family man".
AP McCoy said: "He was a little bit like myself at times, he could be grumpy enough, but was very good-humoured, a fantastic, brilliant rider."