Herein, we report a series of oligomeric chain extender-derived AEMs (QPP-b-PSK-w-TMA) with increased molecular weights. The QPP-b-PSK-w-TMA membranes showed excellent polymer main-chain stability as well as outstanding hydroxide conductivity, 129 mS cm⁻¹ at 80 °C, which is 1.6 times higher than that of FAA-3, moreover, the QPP-b-PSK-w-TMA also exhibited remarkable thermally stable rheological properties originating from the main chain structure. Using the QPP-b-PSK-3.5-TMA membrane, we demonstrated that a high performance low platinum group metal (PGM)-loaded AEMFC showed a high specific power of 4.9 W mg_PGM⁻¹, which is the highest value among those reported for the state-of-the-art AEMFCs with PGM-based electrodes. In addition, an AEMWE with the QPP-b-PSK-3.5-TMA membrane showed a high performance of 4.0 A cm⁻² at 1.9 V under 90 °C and durable performance with a low degradation rate of 1.2 mV h⁻¹ for 100 h despite the use of the NiFe catalyst under 80 °C.