Two-step processes are used in the deposition of the Cu2ZnSnS4 (CZTS) thin films. First, the CZTS precursors are deposited on Mo and soda-lime glass (SLG) substrates at different temperatures using the spray pyrolysis technique, followed by annealing in sulfur and tin atmosphere at 580 °C for 30 min. The impact of the substrate temperature and annealing step on structural, morphological, and optical properties of the prepared layers was studied. The annealing process improves the poor structural, morphological, and optical properties of as-deposited CZTS thin films by promoting grain size and crystallinity. The sprayed layers showed fine grains structure. A compact and large grains structure CZTS layers were formed upon annealing accompanied by improvement in crystallinity. The evaluated energy bandgap in the range of 1.5 eV indicates a suitable absorbing material for solar cell applications. The obtained results provide useful information and a better understanding of the influence of substrate temperature and the annealing process on the physical properties of sprayed CZTS layers.