A three-parameter optical sensor based on a tilted fiber Bragg grating is proposed. Through the monitoring of the wavelength shift of the core mode resonance and the ghost mode resonance, it is possible to discriminate strain and temperature. In addition, the refractive index can be determined by calculating the normalized transmission spectrum area. With the current approach, resolutions of up to $5.7\times {10}^{-4}$ , $4\mathrm{\mu \epsilon }$ , and $3.1°\mathrm{C}$ were achieved, for refractive index, strain, and temperature, respectively. The developed sensor can be an important tool in several areas of engineering, namely, biomedical, biological, and environmental sensing.