The pipeline leak detection and repair device is an autonomous machine that travels through a pipeline to detect very small leaks therein. The device also repairs those leaks with an on-board repair component. The repair occurs nearly simultaneously with the leak detection as the device passes the leak. The device includes a plurality of thin, flexible sensor leaves in a radial array. The leaves are positioned to place them nearly in contact with the inner surface of the pipe wall. Each leaf includes two sensors installed on its opposite surfaces. Flexure of the leaf due to changes in pressure gradient as the leaf passes a leak results in signals from the sensors being sent to an onboard processor. The processor determines the position of the affected leaf, and rotates a repair component to apply a pressure-sensitive tape patch over the leak as the repair component passes the leak.