The 33-year-old former model, who brought vitality and elegance to the eventing scene, was riding in a novice section of the Savernake Horse Trials, near Marlborough, in Wiltshire, when the accident occurred at a double of offset rails. She was married with two children aged eight and six.
Beckett, who finished 24th in last year's World Equestrian Games, was one of 16 riders on the British World Class Performance squad.
Beckett, who was based at Wiggington, near Banbury, lectured in Equine Studies at Warwickshire College and took horses for breaking and schooling as well as competing herself.
This was the 13th fatality at a British event since April 1982 - and the first since September 1997 when Irishman Sam Moore died from injuries sustained at the Blenheim Horse Trials.