Courses designed by Tom Dunn (he claimed over 130) are predominantly to be found in England, with a few continental European exceptions. His best known work includes, but is not limited to: Biarritz Le Phare GC (France); Broadstone (Dorset); Came Down (Dorset); Dinard (France); Felixtsowe Ferry (Suffolk); Reigate Heath (Surrey); Royal Worlington & Newmarket (Suffolk); Sheringham (Norfolk); Weston-super-Mare (Somerset) and Woking (Surrey).

Dunn grew up in a golfing family, his father Willie Dunn Sr was a professional golfer, club maker and greenkeeper, who played in many challenge matches, partnering his twin brother Jamie. Young Tom followed in the family footsteps, serving an apprenticeship under his father, and also becoming a professional golfer and club maker. Tom married Isabella Gourlay; his father had previously been apprenticed to the Gourlay family.

Tom Dunn (like his younger brother Willie Jr) made his mark in the game as a golf course designer. He laid out a large number of courses (he claimed over 130), helping to satisfy the insatiable appetite for the game that developed in the 1880s and '90s. He also played a significant part in the development of inland "heathland" courses, especially around London. Woking GC, a Tom Dunn layout that opened for play in 1893, was one of his first heathland courses, and the first such course located just outside the capital.

Tom Dunn's children also followed significant careers in golf. His daughter Isabella May Gourlay Dunn (1880-1948) also became a course designer, golf professional, golf instructor and was an influential force in the promotion of women's golf. "Queenie" as she was known, was born in Wimbledon Common, nr London and emigrated to the United States in 1915, with her husband Willie Webb, a golf professional. Tom's son Seymour Gourlay Dunn became a renowned golf course architect and very influential golf instructor in the United States. John Duncan Dunn (born 1882) also headed stateside, where he teamed up with Tom's brother, Willie Dunn Jr, in a very successful golf equipment manufacturing business.