With the ever-growing global demand for renewable energy sources, Cu₂ZnSnS₄ (CZTS) thin films can complement the existing Silicon-based photovoltaic (PV) cell market. However, low carrier mobility and lifetime, non-uniformity, and defects in the film structure have reduced the widespread application of CZTS. During the manufacture of CZTS solar cells, the initial as-deposited films have a nanocrystalline structure. Therefore post-deposition annealing is critical to make the efficiency of the cell commercially viable. Conventional furnace annealing methods have failed to enable this technology's commercialisation, and the heating of the complete PV cell limits the selection of available substrates. This research explored alternative approaches, specifically diode and pulsed fibre laser annealing for CZTS films deposited on flexible Mo foils in different gas atmospheres. SEM, XRD, and Raman spectroscopy techniques were used to analyse the laser-annealed samples. Processing parameters were established by which grain enlargement was observable with the pure CZTS phase retained. The key findings build confidence in laser annealing as an alternative method to enhance the crystallinity, surface morphology, chemical composition, and electrical properties of CZTS thin films for next-generation PV cells. Laser annealing can potentially reduce the reliance on vacuum furnace heating of PV cells and enable annealing on more thermally sensitive substrates.