Although nanoscale sensors provide valuable data at finer levels, their size limitations impose difficulties in designing nanoscale systems. The limitations in the hardware part of such systems consequentially affect the software part, too. Routing, being one of the main functions of the communication software of nanosensors, requires customized design, where constraints like the energy efficiency have to be considered. With the knowledge that communication is the most energy-consuming operation for the sensor networks in general, the importance of routing protocol becomes clear. With this motivation, the existing routing protocols for the wireless nanosensor networks are reviewed. Comparison of the existing protocols, followed by extensive discussions on the proposed energy-aware protocol based on the “backward-learning” paradigm have been also performed in this chapter. Simulations are carried out in ns-3 by using a Nano SIM package. Results are listed to show the efficiency of the proposed method in terms of the energy use and the packet statistics.