We propose and demonstrate a single- and dual-wavelength switchable erbium-doped fiber laser (EDFL) by utilizing intracavity polarization selective filters based on tilted fiber gratings (TFGs). In the cavity, one $45°$ TFG functions as an in-fiber polarizer and the other $77°$ TFG is used as a fiber polarization dependent loss (PDL) filter. The combined polarization effect from these two TFGs enables the laser to switch between the single- and the dual-wavelength operation with a single-polarization state at room temperature. The laser output at each wavelength shows an optical signal-to-noise ratio (OSNR) of $>60\mathrm{dB}$ , a side mode suppression ratio (SMSR) of $>50\mathrm{dB}$ , and a polarization extinction ratio of $\sim 35\mathrm{dB}$ . The proposed EDFL can give stable output under laboratory conditions.