Cystic fibrosis (CF) is an inherited condition characterised by thick mucus accumulation in the lungs, leading to recurrent pulmonary infections, inflammation and lung damage. Dornase alfa (Pulmozyme®), or recombinant human deoxyribonuclease I (rhDNase), is a mucolytic agent commonly used to decrease mucus viscosity and improve the lung function of CF patients. However, its delivery via nebulisation presents notable limitations: the process is time-intensive, requires refrigeration, and must be performed in a stationary setting—factors that collectively contribute to a high treatment burden and often reduced patient adherence. Inhalable dry powder formulations offer a promising alternative, combining portability, improved stability, and ease of use. This study explores the feasibility of converting commercially available rhDNase for nebulisation into a dry powder formulation, using bovine DNase I as a model system. Co-spray drying of bovine DNase I with sodium chloride and calcium chloride dihydrate was performed at a mass ratio of 1:8.77:0.15. A quality-by-design approach, utilizing a 23 full-factorial design of experiments, was employed to assess the effects of critical process parameters - solution flow rate, atomising air flow rate, and outlet temperature - on quality attributes, including particle size distribution, yield, and protein recovery. The resulting spray-dried powders demonstrated suitable in vitro aerosolization characteristics suitable for pulmonary delivery, with enzymatic activity retention of up to 94%. In vitro tests on the most promising formulation showed no cell toxicity, supporting its potential for pulmonary delivery, as a patient-friendly alternative for CF therapy.