Perovskite solar cells are a promising technology for emerging photovoltaic applications that require mechanical compliance and high specific power. However, the devices suffer from poor operational stability. Here we develop lightweight, thin (<2.5 μm), flexible and transparent-conductive-oxide-free quasi-two-dimensional perovskite solar cells by incorporating alpha-methylbenzyl ammonium iodide into the photoactive perovskite layer. We fabricate the devices directly on an ultrathin polymer foil coated with an alumina barrier layer to ensure environmental and mechanical stability without compromising weight and flexibility. We demonstrate a champion specific power of 44 W g−1 (average: 41 W g−1), an open-circuit voltage of 1.15 V and a champion efficiency of 20.1% (average: 18.1%). To show scalability, we fabricate a photovoltaic module consisting of 24 interconnected 1 cm2 solar cells and demonstrate energy-autonomous operation of a hybrid solar-powered quadcopter, while constituting only 1/400 of the drone’s weight. Our performance and stability demonstration of ultra-lightweight perovskite solar cells highlight their potential as portable and cost-effective sustainable energy harvesting devices.