In this study, an all-fiber polarization-dependent device based on a 45° radiated tilted fiber grating (RTFG) is reported. Owing to its unique polarization-dependent mode coupling characteristics, this device can be used as an ideal all-fiber polarizer, polarization-dependent coupler, and all-fiber diffraction device. Based on the volume current method, the polarization coupling theory for tilted fiber gratings is established. The polarization radiation coupling, diffraction splitting, and polarization characteristics of the 45° RTFG are systematically analyzed theoretically and experimentally. Simulation and experimental results show that the transmission and radiation of the 45° RTFG exhibit good polarization function. The 45° RTFG with a length of 24 mm shows a polarization extinction ratio (PER) of 22 dB at a wavelength of 1550 nm, and the 3-dB bandwidth is more than 300 nm. Moreover, the grating with different PER can be prepared by changing the grating length. The radiation mode distribution of the 45° RTFG is measured, which indicates a quasi-Gaussian profile and exponential reduction along the azimuthal and axial directions, respectively. The spatial diffraction angular dispersion is approximately 0.054 (°)/nm, which is consistent with the simulation result. The 45° RTFG has potential application prospects.