Trivalent Al³⁺-doped samples of magnetite (Al_xFe_3−xO₄, 0.01 ≤ x ≤ 1.0) were produced by wet chemical method. The X-ray diffraction studies confirmed the formation of a single-phase inverse spinel-type structure. Particles having spherical morphology and size range lying between 4 and 25 nm were observed during transmission electron microscopic investigation. Magnetic measurement displayed increase in saturation magnetization with a maximum value of ~62 A·m²/kg for x = 0.1, and thereafter, it started decreasing with increased concentration of Al. The temperature during magnetic hyperthermia got stabilized near therapeutic range (~315 K) for the samples such as x = 0.01, 0.5, 0.7, and 1.0 at various external alternating current magnetic fields.