A simple and modified solvothermal method using oxalate precursor, used to synthesize Cd1−xNixO (x = 0.047, 0.102, and 0.163) nanoparticles and their phase structure, morphology, optical and magnetic properties, have been investigated. X-ray diffraction studies revealed that as-prepared Ni-doped CdO solid solutions are highly crystalline and stabilized in a monophasic cubic CdO structure. X-ray diffraction and ICP-MS studies confirmed the incorporation of Ni2+ in a CdO matrix. The average grain size was found to be 30, 15, and 11 nm, respectively, using transmission electron microscopic studies. High surface area in the range of 118–143 m2/g has been achieved for these solid solutions using the multipoint BET method, which increases on increasing Ni concentration in Cd lattice site. The optical band gap of these solid solutions shows red shift to the undoped CdO. Ni-doped CdO nanoparticles exhibit co-existence of paramagnetism and ferromagnetism.