To increase the anti-wear (AW) and anti-scuffing possibilities of commercially available lithium grease, this paper proposed enriching the original composition with functionalised carbon nanotubes (CNTs) at a concentration of 0.1% ( w/ w). The CNTs were modified by decorating them with nanoparticles of two metals with established tribological potential: copper and nickel. The AW and extreme-pressure properties were determined using the customised ISO-20623 test on a four-ball apparatus. The AW properties were determined using the standardised parameter MWSD (mean wear scar diameter) and the anti-scuffing properties using the last non-seizing load. The greases enriched with nanoadditives showed better AW properties compared to the reference grease at higher loads (1–1.2 kN). Particularly favourable results were observed for grease with the addition of Cu-decorated CNTs, for which the MWSD values were more than 50% lower than the reference. Optical microscopy, SEM and TEM microscopy with EDS analysis, and Raman spectroscopy were used to identify the wear mechanisms and characterise the role of nanoadditives in the lubrication process.