This research investigates the impact of carbon nanotubes on the mechanical properties of both treated and untreated jute fiber-reinforced polyester composites. Jute fibres were treated with alkali. Composites with treated and untreated jute fibers were prepared with 5%, 10%, and 15% fiber loading, with and without carbon nanotubes at concentrations of 0.2%, 0.4%, and 0.6%. Results indicate an increase in tensile, flexural, and impact strength with higher fiber loading, with the most significant improvement observed in the 0.6% carbon nanotube-reinforced composites. The enhanced mechanical properties can be attributed to strong interfacial bonding, as demonstrated by SEM images.