Soil cadmium (Cd²⁺) stress adversely affects the plant growth, yield and physiology. Plant growth-promoting bacteria (PGPB) are able to improve the plant growth in metal contaminated soils. The objective of the current study was to evaluate the phytobeneficial and bioremediation potential of a Cd-tolerant bacterial strain isolated from the wastewater collection point of Chakera, Faisalabad, Pakistan. The Serratia marcescens CP-13 was identified through 16S rRNA gene sequence analysis, exhibited a significant potential for inorganic phosphate solubilization, indole-3-acetic acid production and 1-aminocyclopropane-1-carboxylic acid deaminase activity. Afterwards, a pot experiment was conducted to evaluate the effects of S. marcescens CP-13 inoculation on spinach growth under Cd stress. The soil was spiked with Cd at the rates of 0, 5 and 10 mg kg^-1 and the experiment was repeated twice. Without inoculation of S. marcescens, Cd stress significantly reduced the plant biomass as well as the quantity of proteins and photosynthetic pigments due to enhanced H₂O₂, MDA and impaired nutrient homeostasis. Subsequently, S. marcescens CP-13 increased the plant fresh and dry biomass, plant antioxidation capacity, whereas it decreased the lipid peroxidation under Cd stress. In parallel, S. marcescens inoculation conferred the Cd stressed plants to accumulate higher nutrients (K, Ca, P, Mg, Fe and Mn). In conclusion, S. marcescens inhibited the uptake of Cd, maintained the optimum level of nutrients by limiting the lipid peroxidation of plasmalemma and, thereby, enhanced the growth of S. oleracea under Cd stress. Spinach plants exhibited lower values of bio-concentration factor and translocation factor (<1) for Cd under S. marcescens CP-13 inoculation. S. marcescens CP-13 inoculation together with spinach could be used for phytostabilization of metal-contaminated rhizosphere/soil colloids.