Due to the low capacity, low working potential, and lithium coating at fast charging rates of graphite material as an anode for Li-ion batteries (LIBs), it is necessary to develop novel anode materials for LIBs with higher capacity, excellent electrochemical stability, and good safety. Among different transition-metal oxides, ABsub.2Osub.4 spinel oxides are promising anode materials for LIBs due to their high theoretical capacities, environmental friendliness, high abundance, and low cost. In this work, a novel, porous Znsub.0.5Mgsub.0.5FeMnOsub.4 spinel oxide was successfully prepared via the sol–gel method and then studied as an anode material for Li-ion batteries (LIBs). Its crystal structure, morphology, and electrochemical properties were, respectively, analyzed through X-ray diffraction, high-resolution scanning electron microscopy, and cyclic voltammetry/galvanostatic discharge/charge measurements. From the X-ray diffraction, Znsub.0.5Mgsub.0.5FeMnOsub.4 spinel oxide was found to crystallize in the cubic structure with Fd3¯m symmetry. However, the Znsub.0.5Mgsub.0.5FeMnOsub.4 spinel oxide exhibited a porous morphology formed by interconnected 3D nanoparticles. The porous Znsub.0.5Mgsub.0.5FeMnOsub.4 anode showed good cycling stability in its capacity during the initial 40 cycles with a retention capacity of 484.1 mAh gsup.−1 after 40 cycles at a current density of 150 mA gsup.−1, followed by a gradual decrease in the range of 40–80 cycles, which led to reaching a specific capacity close to 300.0 mAh gsup.−1 after 80 cycles. The electrochemical reactions of the lithiation/delithiation processes and the lithium-ion storage mechanism are discussed and extracted from the cyclic voltammetry curves.