In this study, Ni2-xCoxMnSb full-Heusler alloys (1.00 <= x <= 1.75) were prepared by arc melting process, and examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and SQUID. The L2(1)crystal structure of the synthesised Heusler alloy was confirmed by XRD patterns, and it was observed that the use of Co instead of Ni caused a decrease in the interatomic distance. The magnetisation results revealed that all samples show ferromagnetic (FM) behaviour, and substitution Co for Ni leads to increasing FM interactions in the samples. The calculated magnetic moment per formula unit increase from 4.38 mu B(x = 1) to 5.17 mu B (x = 1.75). On the other hand, the increase in FM interaction caused an increase in ferromagnetic-paramagnetic (PM) phase transition (T-C) temperatures from 513 (x = 1) to 568 K (x = 1.75). The ability to control the Curie temperature with Co substitution makes these alloys suitable candidates for future spintronics and magnetoelectronic applications.