Lois Lister studied Economics at Cambridge University, England and at Radcliffe College, Harvard, in the United States before moving to Canada in the 1940's. In 1953 she decided to completely change her career path and began her work as a Landscape consultant in Toronto. Out of respect for the profession of Landscape Architecture she did not refer to herself as Landscape Architect until she was one of the first women accepted into the Canadian Society of Landscape Architects.

Lois Lister specialized in designing private residential gardens but she did have a public persona. In the mid 1950's she appeared regularly on the CBQ Television programme "Living" and she published intermittently in The Globe & Mail and Chatelaine Magazine. In 1957 she was invited to serve the newly formed Metropolitan Toronto and Region Conservation Authority as an appointee to the Conservation Areas Advisory Board. She served the board until 1978 and was fundamental in helping to develop a strategy for the maximum use of conservation areas. Lois Lister frequently represented the interests of Canadian Landscape Architects at international conferences in Europe, and North and South America. She was very interested in all the details of a landscape including the furnishings. This interest lead her to design a line of Ontario Design Award winning fibreglass planters which were manufactured under the name Gardenglass.

Lois Lister designed gardens for many of Toronto's prominent citizens including Paul J. Phelan, George Black, Montague Black and Conrad Black (including the Black family plot in Mt. Pleasant Cemetery), H.N.R. Jackman, Anthony Adamson, Joe Rotman the Bacardi family, George Chater, William Heaslip, and Karl Heisey of Burlington. She worked with many architects ( Horne Residence: Ron Thom, Klamer Residence: Irving Grossman) but always felt that her work with Napier Simpson was amongst her best. There are corners in Rosedale and Forest Hill (Toronto) where you could see her gardens in every direction you looked. Her gardens, including her use of stone and paving detailing and planting design, defined the appearance of the more affluent parts of the city.

Later in her career Lois Lister resisted being published because she felt that most articles did not adequately discuss the subtleties of landscape design and because she felt it was appropriate to protect her clients' privacy. Her one exception to this rule was the American magazine Garden Desiqn*. In 1984 she was included in the company of such designers as Roberto Burle Marx, John Brookes, E.E. Bye and Russell Page, in the American Society of Landscape Architectibook Garden Desiqn (Prentice Hall) as an internationally significant Landscape Architect.