Drought is one of the major abiotic stresses to sustainable agriculture and global food security. The present study was conducted to evaluate the integrated effect of algal biochar (BC) and plant growth–promoting rhizobacteria (PGPR) on growth and physiology of maize under deficit irrigations. A pot experiment with different combinations of algal BC and PGPR under three deficit irrigations [field capacity (FC), 75% FC and 50% FC] was performed using maize as test crop. There were three controls without application of algal BC and PGPR under each water deficit irrigation. Both algal BC and plant growth–promoting rhizobacterial inoculation mitigated negative effects of deficit irrigations on maize performance, especially when applied in combined form. Under 50% FC, combined application of algal BC and PGPR significantly increased fresh and dry weights of shoot and root and root length by 2.76, 5.94, 3.24, 13.82, and 4.06 times compared to control, respectively. In case of physiological and nutrient uptake parameters, the same treatment caused the maximum increase in comparison to control. Post-harvest soil analysis also showed a positive treatment effect compared to their respective control. The combined application of algal BC and PGPR could be an effective strategy to improve growth and physiology of maize under deficit irrigations.