Electrode materials that combine the high energy density of batteries and the high power density of supercapacitors become an increasing need for current and near-future applications. Ta2O5 delivers a high theoretical capacity but suffers from unsatisfactory rate capabilities. Here we prepare a structurally disordered Ta2O5 nanoparticle aerogel via a nonaqueous sol-gel process followed by CO2 super-critical drying. The resulting aerogels exhibit large surface area, high porosity, fast ion diffusion, and extrinsically pseudocapacitive Li+/Na+ storage behavior (through surface redox reactions). With these merits, when evaluated as anode material for both lithium-ion and sodium-ion half cells (LIBs and NIBs), the Ta2O5 aerogels show excellent rate capabilities (97.0 and 43.7 mA h g−1 at 5000 mA g−1 for LIBs and NIBs, respectively) and highly stable cycling performance (20000 cycles at 5000 mA g−1 and 10000 cycles at 1000 mA g−1 without obvious capacity fading for LIBs and NIBs, respectively). This work introduces Ta2O5, a typical conversion-type metal oxide without intrinsic pseudocapacitance, as a promising anode material with high extrinsic pseudocapacitance for both LIBs and NIBs, which may open the door to achieve high-rate alkali-ion storage with low synthesis cost for durable microbatteries.