Kay began her career in Victoria before moving to Western Australia in 1978 where she had a 22-year association with the City of Stirling. In 1985 Kay became City Librarian and Manager, Libraries, Arts and Culture, with responsibility for six public libraries, 85 staff, and a $4.5 million dollar budget, as well as community arts, exhibitions and cultural activities for the City. During this time all branches were automated, many of the libraries were relocated or renovated and she initiated a number of innovative programs.
Kay first joined the Library Board of Western Australia in 1990, serving until 1993 as a representative for the Local Government Association. She returned in 1998 and served for a further eight years as representative of the Australian Library and Information Association (ALIA). Her ability and experience was recognised when she was elected Chairman of the Library Board briefly in 2001, and then between 2002 and 2006.
During this time, Kay oversaw major developments in relations between the State Library of Western Australia and Public Libraries Western Australia, including the signing of the Framework Agreement and the allocation of a further $10.3 million in state funds for library resources. Other achievements included the launch of the Better Beginnings program and the establishment of the Historical Records Rescue Consortium.
The Kay Poustie Scholarship is named in her honour and gives library professionals the opportunity to undertake research.