With low latency and collision-free communication, wavelength-routed optical networks-on-chip (WRONoC) become an effective solution to the growing demands for multi-core communications. Microring resonators (MRRs), the primary optical components in WRONoC, are susceptible to process variation. Under process variation, the MRR’s transmission spectrum shifts, results reduced signal power and increased crosstalk. However, the impacts caused by process variation have not yet been considered in WRONoC designs. In this work, we propose a methodology to optimize the MRR radii and signal wavelengths to counter process variation. Specifically, we construct analytical models of expected signal power under MRR process variation and develop optimization methods to maximize the expected signal transmission power in WRONoC. Results show up to 7.51 dB improvement in worst-case expected signal transmission power compared to designs that do not consider process variation.