The main goal of this study is to comprehend the effect of the composition change on crystallization characteristics, thermal, physical, and magnetic properties of glasses with the general formula (35 − x) Li2O − (5 + x) NiO − 60 P2O5 (x = 5, 10, and 15 mol%). The XRD results indicated that Li4P4O12, Li6P6O18, Ni2P2O7, Ni2P4O12, and Li3P crystalline phases were formed in the glass ceramics. The NiO/Li2O replacement led to an increase in the coherence of the glass structure. Density values for the glass and glass–ceramic samples ranged from 2.38 to 2.49 g/cm3 and from 2.41 to 2.53 g/cm3, respectively. Coefficients of thermal expansion CTE of the glasses were varied from 157 × 10−7 to 96 × 10−7 °C over the temperature range of 25–250 °C. However, CTE of the glass–ceramic was ranged from 183 × 10−7 to 129 × 10−7 °C over the temperature range of 25–500 °C. VSM analysis for the glasses revealed that the NiO/Li2O replacement led to a decrease in the magnetic parameters of the materials. Contrariwise from VSM hysteresis loops of glass–ceramic, it was found that the magnetic parameters increased with the addition NiO instead of Li2O. The results indicated a great potential of the prepared glasses and glass ceramics as promising soft ferromagnetic materials that can be used in different magnetic applications.