Cretaceous granitoid plutons of the Seagull and Teslin plutonic suites, east of Teslin, are evaluated for their potential radiogenic heat production. The Seagull suite comprises ultra-fractionated, A-type granites dated at ca. 103–101 Ma that have anomalous average heat production values (A) of 7.9 to 9.9 µW/m3. The Teslin suite is older (ca. 121–109 Ma) and characterized by more intermediate granodiorite compositions that mostly have average A values of 2.0 µW/m3, closer to global averages. Locally, anomalous A values of 4.5 to 11.4 µW/m3 are associated with younger (ca. 110–108 Ma), more evolved granitic phases of the Teslin suite. The 3D inversion of Bouguer gravity data provides models that constrain the subsurface density character and extents of the Hake and Seagull batholiths, and estimated volumes of ~4624 and 2744 km3, respectively. The combination of these results suggests that potential heat energy of ~36.5 MWt may be contained in the Hake batholith, and as much as 27.2 MWt in the Seagull batholith.