In this paper, a compact 1 × 3 photonic crystal (PC) router is proposed to act as the basic building block to realize scalable wavelength-selective non-blocking routing. Compared with N × N routers constructed with traditional basic building blocks (1 ×2 or 2 ×2 wavelength routers), the comprehensive performance of the device can be improved. Based on four 1 × 3 router units, a 4 × 4 wavelength-selective non-blocking PC router with a footprint of 1060.4 µm2 is designed. The number of resonators in the configuration is only one-half of that in 4 × 4 PC routers reported in the available literatures. For the non-blocking routing function, the signal-to-noise ratios (SNRs) of the 4 × 4 PC router are 18.65–22.86 dB for all 32 optical links of the eight routing states at 1530 nm. For the wavelength selective routing function, the insertion loss and crosstalk of the 4 × 4 PC router are 0.474–0.575 dB and 11.029–36.409 dB respectively. More complex high-radix optical routers can be easily constructed with the proposed router unit, which is an attractive option for use in the future photonic networks-on-chip.