The extensive application of GaSe in optoelectronic devices has generated great enthusiasm for the study of their fundamental properties. Despite its high quantum yield and superb nonlinearity, the intrinsic out-of-plane transition dipole of excitons in GaSe leads mainly to in-plane photoluminescence (PL) emission, which results in poor detection efficiency normal to the sample surface. Here, we demonstrate a practical strategy for boosting and modulating the PL of GaSe by transferring it onto dielectric linear Bragg gratings (LBGs), achieving a significant 42-fold enhancement in PL at room temperature. Furthermore, the use of the LBG results in strong linear polarization of the original isotropic PL emission. In addition, temperature-dependent experiments indicate that the LBG results in maximum modulation of PL at 605 nm, an up to 150-fold increase. Through this work, we provide a facile method to enhance the exciton recombination and light outcoupling efficiency of GaSe, which can be further applied to other van der Waals layered materials with out-of-plane optical dipole transition for enhanced optoelectronic device performance.