A novel Mn4+-doped strontium lanthanum gallate red phosphor SrLaGaO4:Mn4+ has been successfully prepared via the conventional solid-state reaction method. Phase purity, photoluminescence excitation/emission spectra, concentration quenching, decay curves, and temperature-dependent photoluminescence have been investigated systematically. SrLaGaO4:Mn4+ phosphor exhibits broad excitation band from 250 to 600 nm and emits intense red light centered at 716 nm arising from spin-forbidden transition, E-2 (4)A(2) of Mn4+. The optimal dopant concentration of Mn4+ is determined to be 0.2 mol%. Dipole-dipole interaction is supposed to be the mechanism of concentration quenching. The crystal-field strength Dq, the Racah parameters B and C, and the nephelauxetic ratio (1) of SrLaGaO4:Mn4+ have been calculated according to its luminescent spectra. Our systematic investigation on this new phosphor can provide a reference for the development of red-emitting phosphor.