During World War II, he was a volunteer executive in the Canadian government's war effort. He was appointed by C. D. Howe to the executive committee of the Department of Munitions and Supply and would be appointed by Winston Churchill to run the British Supply Council in North America. He came close to losing his life when, in December 1940, the ship he was on was torpedoed while crossing the Atlantic. He and others on the sinking ship were rescued by a captain who broke regulations to pick them up.
Through his war-time service, Taylor became connected to top businessmen from across Canada and around the world. At war's end, he founded Argus Corporation, becoming the investment company's majority shareholder by rolling Canadian Breweries stock into the new entity. Over the years, he gained control of many of his country’s greatest companies such as Canadian Food Products, Massey-Harris, Orange Crush, Standard Chemical, Dominion Stores, British Columbia Forest Products Limited, Domtar Paper, Standard Broadcasting, and Hollinger Mines Limited. He operated the business until 1971 and would sell his shares to Paul Desmarais. During the highest point of his career, he was one of Canada's richest businessmen.
E.P. Taylor also pioneered the concept of gated communities in exotic places. He founded the highly exclusive Lyford Cay gated community in 1959 and its 'Lyford Cay Club' on New Providence island in the Bahamas. The Lyford Cay Club is home to some of the world's wealthiest people.
In 1948, E.P. Taylor and a small group of fellow alumni established the McGill University Alma Mater Fund, inviting all graduates to give annual donations and thereby "make of themselves a living endowment."
In the 1950s, E. P. Taylor and his wife, Winnifred, began breeding Thoroughbreds. Their involvement led to the acquisition of Parkwood Stable near Toronto and then Windfields Farm at Oshawa, Ontario. The Taylor thoroughbred horse breeding operation produced Northern Dancer, the greatest sire of the 20th century. In 1970, he was the world's leading horse breeder measured by money won. He was president of the Ontario Jockey Club from 1953 to 1973 where he consolidated numerous money-losing tracks throughout the province into fewer, but viable businesses. He was voted thoroughbred racing's man of the year in 1973 and the following year was elected to Canada's Sports Hall of Fame. In 1977 and 1983 he was named the winner of the Eclipse Award for Outstanding Breeder as the leading thoroughbred breeder in North America. Taylor's horses won 15 Queen's Plate races and were named Canadian Horse of the Year nine times. He was also a founder of the Jockey Club of Canada.
Windfields Estate was Taylor's home and was situated at 2489 Bayview Avenue in North York, Ontario (now part of Toronto). It is now the site of The Canadian Film Centre. The 25 acre estate has been preserved as a heritage site. The British Royal Family often stayed at Windfields when they visited Toronto. The last royals to stay there were the Queen Mother in the summer of 1974 and Prince Charles and Princess Diana. There were many maids, two gardeners and a house manager who worked at the residence.