The purpose of this thesis was to characterize the thermal biology of three important fish species in the Laurentian Great Lakes using biologging and biotelemetry tools. Thermal patterns and occupancy models for adult walleye from Lake Erie and Huron were determined using biologging to assess the effects of sex, fish size, diel periods, and location (i.e., lake). The depth and temperature used by different sizes of northern pike and largemouth bass in the Toronto Harbour of Lake Ontario were studied with biotelemetry. Occupancy models revealed northern pike occupied deeper depths, while experiencing similar thermal experiences throughout the majority of the year compared to largemouth bass. As a whole, this thesis enhances the understanding of the thermal biology of free-swimming fish in the Laurentian Great Lakes informing the management of three economically and socially important fish species.