Career
As a 19-year-old player, Van Horn reached the finals of the 1939 United States. Nationals only to lose to Bobby Riggs in just 56 minutes (6–4, 6–2, 6–4). One of the high points of his career was a crushing defeat (6–0, 6–2, 6–1) of the great Bill Tilden at a match between United States. and British Empire service teams at Wimbledon in July 1945, supposedly the worst drubbing of Tilden"s career — Tilden, however, was 52 years old at the time while Van Horn was 25. He was ranked as high as World Number.
5 in the professional ranks (the Professional Players Association, instated by Bill Tilden) in 1946.
Gordon Lowe ranked Van Horn as World Number. 9 for 1939 in his amateur rankings.
He lived briefly in Atlanta, Georgia., where he had been hired as Head Tennis Professional at the Piedmont Driving Club. In 1951, he moved to Puerto Rico as a coach at the Caribe Hilton Swim and Tennis Club, where he worked with many promising juniors, the most notable being Charlie Pasarell who was ranked Number.1 in the United States. in 1967 who he continued to coach on the main tour, another notable junior was Manuel Diaz, later to become a star on the University of Georgia tennis team and UGA coach.
His career as a coach spawned institutions such as the Welby Van Horn Tennis Academy in Boca Raton, Florida, and Welby Van Horn Tennis programs in a number of locations.