The production of polyethylene terephthalate (PET) textiles, commonly known as polyester, is an energy and water-intensive process, particularly during the dyeing and finishing stages, leading to significant carbon emissions and wastewater filled with toxic chemicals. Conventional dyeing processes consume large volumes of water and energy, making them environmentally harmful. Innovative methods like hydraulic spray atomizer offer a more sustainable alternative by reducing water and chemical usage, thus minimizing waste and environmental impact. This study explores the hydraulic spray dyeing process parameters, including pre-treatment, dyeing, pre-drying, and fixation steps for three different polyester fabrics. The objective is to achieve resource-efficient dyeing with comparable results to traditional methods, and to compare effectiveness of a combined pre-treatment and dyeing approach with a two-step spray application of pre-treatment and dyeing. Pre-treatment of the polyester fabrics with chemical hydrophilizing agents by spray application showed to improve the hydrophilic character and wetting capacity of three polyester fabrics—P75, P600, and Kibo based on reduced water contact angle measurements and increased vertical wicking rates. A pre-treatment also showed to enhance the K/S values of the three different polyester fabrics. The addition of a pre-drying step showed some indication of reducing disperse dye migration, and enhanced color strength of the Kibo fabrics. Spray dyed samples maintained dyeing quality comparable to padded samples. One-step spray processes demonstrated comparable or improved color properties and durability to fastness to washing and abrasion in comparison to two-step processes. The results demonstrate that the hydraulic spray atomizing system is viable for both dyeing and pre-treatment of polyester fabrics. Furthermore, this lays the groundwork for innovation in wet textile processes of polyester fabrics using this resource-efficient alternative, aiming towards sustainable textile production and dyeing.