The addition of complexing agents to the electrolyte has been shown to be an effective method to enhance the discharge performance of magnesium−air batteries. In this work, four complexing agents: citric acid (CIT), salicylic acid (SAL), 2,6-dihydroxybenzoic acid (2,6-DHB), and 5-sulfoisophthalic acid (5-sulfoSAL) were selected as potential candidates. Through electrochemical tests, full-cell discharge experiments, and physicochemical characterization, the impact of these complexing agents on the discharge performance of magnesium−air batteries using AZ31 alloy as the anode material was investigated. The results demonstrated that the four complexing agents increased the discharge voltage of the batteries. Notably, SAL could significantly improve the anodic efficiency and the discharge specific capacity, achieving an anodic efficiency of 60.3% and a specific capacity of 1358.3 mA·h/g at a discharge current density of 10 mA/cm².