Understanding and untangling magnetic materials are essential to implanting these materials for practical industrial applications. This work demonstrates how manganese (Mn) doping can significantly advance cobalt ferrite's magnetic and optical characteristics. We applied the hydrothermal approach to synthesize cobalt ferrite nanostructures, followed by Mn doping, to acquire CoMnxFe2−xO4 (0 ≤ x ≤ 0.1) nanostructures. The crystal structure of all the specimens confirms the formation of Fd-3 m space growth with a typical cubic structure. The estimated crystallite size values vary between 19.8 and 25.8 nm, and the lattice parameter significantly enhances from 8.31 Å to 8.38 Å as a result of Mn substitution. The fast Fourier transform infrared spectroscopy (FTIR) was performed between 400 and 4000 cm-1. The lattice vibrations ranging υ1 = 614–607 cm-1 and υ2 = 428–426 cm-1 were assigned to tetrahedral and octahedral sites, respectively. The high-resolution transmission electron microscopy (HRTEM) analysis further confirms the crystalline structure of CoMnxFe2−xO4. The room temperature magnetic measurements investigate that the magnetic coercivity of CoMn0.2Fe1.8O4 nanostructures is maximum (∼ 800 Oe) which was opted for temperature-dependent measurements. The low-temperature magnetic characteristics agree with Bloch's and Kneller's laws for saturation magnetization and coercivity of CoMn0.2Fe1.8O4 nanostructures. The optical properties confirm a blueshift and slight increment in bandgap energy of CoMnxFe2−xO4 nanostructures.