Wavelength-tunable mode-locked fiber lasers are highly desirable in diverse applications, such as optical parametric generation (OPG), optical frequency comb (OFC) generation, and bio-imaging. Wide operating bandwidth and high-quality mode-lockers are essential for enhancing the spectral tuning range. Wavelength tuning can be accomplished either through intra-cavity effects or by external modulation. Moreover, implementing an all-polarization-maintaining (all-PM) laser cavity configuration helps to improve environmental robustness. This chapter introduces the optical characteristics of wavelength-tunable mode-locked PM fiber oscillators using various pulse-picking techniques across different bands. It focuses on the tunable range and tuning methods of the central wavelength in the mode-locked spectrum, which is critical for applications such as coherent anti-Stokes Raman scattering (CARS) microscopy.