The structural, optical, and magnetic qualities of Cd_1-xMn_xZnO₂ nanocomposites with (0.00 ≤ x ≤ 1.00) are investigated and the paramagnetic ferromagnetic transition is explained. Two series (effect of annealing and composition) were synthesized using the hydrothermal method and then annealed for 3 h at annealing temperatures (T_ann) of 400 °C or 600 °C. It is found that an increase in either x or T_ann correlates with significant change in unit cell volume (V), crystallite size (D_hkl), Debye temperature (θ_D) and energy gap (E_g). Further, the samples at x = 0.60 show a sudden change or inflection point in the behavior of these parameters is detected. Furthermore, the values of E_g and D_hkl for the x = 0.60 sample are independent of the chosen T_ann. The weight percent of oxygen increased as x increased, as well as it was higher at 600 °C than at 400 °C. The value of D_hkl at x = 0.40 was increased by increasing T_ann from 20.7 nm to 26.3 nm. Surprisingly, both series of samples exhibit weak paramagnetic properties as x increases to 0.40. However, increasing x to 0.60 yields a strong ferromagnetic signature for both series as well as unusual unsaturated magnetizations of 4.20 and 1.25 emu/g. However, with a larger further than of x above 0.60, the behavior returns to a strong paramagnetic behavior, but with a small percentage of residual hysteresis. These novel outcomes open the way for a possible mechanism for room temperature ferromagnetic (RTFM) and strongly recommend the use of Cd_1-xMn_xZnO₂ nanocomposites, for magnetic imaging, and spintronic devices.