High-quality MoS2 nanostructures were fabricated via chemical vapor deposition technique on SiO2/Si substrate. In this paper, the effect of temperature on the photoluminescence behavior of MoS2 dendritic flake is addressed. We scrutinized the photoluminescence spectra of monolayer and multilayer regions of MoS2 in the temperature range 300 K–680 K. Monolayer and multilayer behavior of MoS2 flakes are confirmed by Raman and Photoluminescence spectroscopy. The excitonic peaks from the multilayer regime become less intense and show a red shift compared to the monolayer PL spectra. Thermally-induced bandgap modulation of MoS2 is demonstrated. The excitonic intensity and peak positions reveal pronounced temperature-dependent changes. These changes are explicable through the increased electron–phonon interaction and lattice rearrangements. Furthermore, first principle calculations are employed to glean insight into the impact of atomic rearrangements on the band gap behavior of MoS2. Our research presents a detailed understanding of thermally driven band gap modulation of monolayer and multilayer MoS2, which is essential for designing optoelectronic devices.