We demonstrated the generation of wavelength-switchable picosecond pulses from a self-seeded Fabry–Perot laser diode that used a tilted fiber Bragg grating (FBG) formed in a graded-index multimode fiber as an external optical feedback element, where wavelength switching was achieved by controlling the modal distribution in the FBG. We measured the reflection spectra of multimode FBGs fabricated with different tilt angles and discussed the effects of the tilt angle on wavelength selection. By using a $20\mathrm{mm}$ long $1.65°$ tilted FBG and a fiber deformer to control the modal distribution in the FBG, we generated $2\mathrm{GHz}$ pulses with a wavelength switchable over 14 wavelengths at a spacing of $\sim 0.8\mathrm{nm}$ .