Abstract The Kerguelen Plateau in the southern Indian Ocean is associated with the Broken Ridge Plateau because of their location with respect to the Southeast Indian Ridge. The Kerguelen Plateau lies south of the mid-ocean ridge and the Broken Ridge Plateau is located at a nearly equal distance to the north. Both plateaus have positive MAGSAT crustal magnetic anomalies associated with them. Comparative modeling of these anomalies places constraints on the crustal nature, the thermal structure, and the tectonic history of the plateaus. Our results support the theory that both plateaus are underlain by oceanic crust, are structurally and lithologically similar, and were formed as a single structure which has since been split by seafloor spreading. Active volcanoes on the northern part of the Kerguelen Plateau suggest that it lies on a hotspot which has raised the Curie isotherm to within the crust of the plateau, decreasing the crustal volume contributing to the magnetic anomaly and thus decreasing the amplitude of the anomaly.