Smart grid technologies have been transforming the power grid operation paradigms by integrating smart sensing devices, advanced communication networks, and powerful computing resources. In addition, data-driven applications have significantly increased in recent years, accelerating the use of smart sensors, such as phasor measurement units (PMU), in power grid monitoring. It necessitates a well-functioning communication network (CN) for PMU measurement data transfer to the control center even in the event of failures. This paper proposes a PMU network routing algorithm to ensure data transfer for control center’s resilient observability to the power grid. The interdependent roles of PMUs in power grid observability is first identified based on the power grid topology. Then, a failure-tolerant routing algorithm is proposed to find data transfer paths in the CN that meets the power grid monitoring needs. The resultant routing paths ensure resilience against single link failure, where the resilience is defined in terms of grid observability. Besides, a cost metric is defined to minimize end-to-end delay in the network to facilitate real-time data transfer. Simulation results verify the superiority of the proposed routing algorithm compared with conventional fault-tolerant routing algorithms that are agnostic to the domain knowledge of power grid observability.