In this study, a structure of graded-index multimode fiber-step index multimode fiber-graded index multimode fiber (GIMF-SIMF-GIMF) was used as a saturable absorber to generate mode-locking in a holmium-doped fiber laser (HDFL). The HDFL was pumped with a compact in-house thulium-doped fiber laser (TDFL) operating at 1943 nm with a maximum output power of 2.1W. Mode-locked pulses with a pulse duration of 1.61ps were successfully generated at the center wavelength of 2091.1nm. The pulse had a repetition rate of 12.79MHz with a bit of fluctuation of 2.09%, indicating stable pulses. The mode-locked pulses were also tunable with a range from 2086.5nm to 2091.1nm by stretching the GIMF part of the SA. This first report demonstrated mode-locking using nonlinear multimode interference (NL-MMI) using GIMF-SIMF-GIMF structure as a saturable absorber in HDFL operating near 2.1µm wavelength.