We report efficient generation of 671 nm red light based on quasi-phase-matched second harmonic generation of 1342 nm in LiNbO₃ waveguides. The design method and fabrication process of the high-quality annealed proton-exchanged periodically poled channel waveguides were presented. A continuous-wave 1.71 mW red light was obtained with a single-pass conversion efficiency of 47%·W^-1·cm^-2, which is 88% that of the theoretical value. While for 1 mW quasi-continuous-laser input, the corresponding peak power being 2 W, the conversion efficiency reached up to 60%. Our results indicate that the annealed proton-exchanged periodically poled LiNbO₃ waveguide is promising for high-efficiency and low power consumption nonlinear generation of visible light.