In 2019, Perkins Bull was inducted into the Brampton Arts Walk of Fame.

As a child, Perkins helped out on the B. H. Bull and Son farm, created by his father Bartholomew Hill Bull. Over the years, it grew to become one of the most successful Jersey cattle operations in the world.

Bull began his educated in Brampton, the town just north of the farm, attending Brampton High School. He earned a Bachelor of the Arts at University of Toronto's Victoria College, then attended law school at Osgoode Hall, where he was called to the Bar of Ontario in 1896. His reputation within the field grew, and in 1908, he was made the youngest King's Counsel not only in Canada, but the entire British Empire.

Bull began to make investments in lumber, oil, western Canada development, and Cuban sugar farming.

During the First World War, Perkins and his wife Maria Brennan Bull opened their Putney Heath, London house to Canadian officers for events, beginning in 1914, and as a convalescence hospital, from 1916 to 1919

After the war, Bull became a lawyer in Chicago.

During a trip to Toronto, Bull was injured in a car. He recovered in a Toronto hospital, and later the family's house in the city. To pass the time, he began to write about the history of the County of Peel.

William Perkins Bull published thirteen books, primarily on Peel County's human and natural history. Among the most popular are From medicine man to medical man (1934, about Peel medical history), From rattlesnake hunt to hockey (1934, about sports in Peel), and From Brock to Currie (1935, about Peel and Canada's military history).

Bull wrote books on the three largest denominations in Peel at the time: Protestantism (From the Boyne to Brampton, 1936), Church of England (From Strachan to Owen, 1938), and Roman Catholicism (From Macdonell to McGuigan, 1939). The latter received praise from Pope Pius XII, an uncommon honour from the Vatican, particularly to an Anglican.

University of Toronto professor W. A. Parks, an old classmate of Bull, reminisced with him as they "sat under an old snow apple tree in my garden..." Parks urged Bull to record the natural history of Peel. He gathered information with the help of experts including university professors and well-loved naturalist Ernest Thompson Seton, walking the fine line between accuracy and accessibility to general readers. The results were From hummingbird to eagle (1936, about birds of Peel), From spring to autumn (1937, about wildflowers of Peel), and From amphibians to reptiles (1938, about ectothermic animals of Ontario).

Perkins Bull's ancestors helped create two Toronto neighbourhoods: Davenport and Downsview. He paid tribute to each settlement in his books, From Oxford to Ontario (1935) and Spadunk: or, From Paganism to Davenport United (1941). His collection of Canadian art (The Perkins Bull Collection, 1934) and a library of Canadian history books he gave to his son (M 'n N Canadiana, 1931) were also the subject of books.

A number of nearly-finished manuscripts were never published. Topics included natural history, Aboriginal people, the United Empire Loyalists, early Peel politics, agriculture, transportation and communication, and Temperance. Son-in-law Harry Symons wrote Fences (1958), based on Bull's research into the topic.

 immense legacy for