Titanium nitride (TiN) with outstanding physical and chemical properties has earned considerable attention. However, few studies have been conducted on the ability of TiN in the ultrafast photonics field. In this study, ultrafast fiber lasers operating at 1.5 and 2 μm were realized using TiN nanoparticles (NPs) deposited onto a D-shaped fiber (DF) as the optical modulator. TiN NPs were synthesized via a reduction-nitridation route. As the TiN-DF saturable absorber (SA) was integrated into the erbium-doped fiber laser (EDFL) and thulium-doped fiber laser (TDFL) cavities, femtosecond pulses of 1532 nm and 1960 nm were obtained with high performance. To the best of our knowledge, the mode-locked fiber laser operating around 1530 nm was realized for the first time. Interestingly, TiN-DF SA in the TDFL could be used as a temperature sensitive device, and a novel temperature sensor was proposed with the sensitivity of 88 pm °C-1. Our results verified that TiN-DF modulators are excellent nonlinear optical devices for ultrafast photonic applications.