The results from magnetotransport and magnetization of nanodiamond doped MgB2-nD(x) are reported. Superconducting transition temperature (T-c) is not affected significantly by x up to x=0.05 and latter decreases slightly for higher x>0.05. R(T) vs H measurements show higher T-c values under same applied magnetic fields for the nanodiamond added samples, resulting in higher estimated H-c2 values. From the magnetization measurements, it was found that irreversibility field value H-irr for the pristine sample is 7.5 T at 4 K and the same is increased to 13.5 T for 3 wt % nD added sample at the same temperature. The J(c)(H) plots at all temperatures show that J(c) value is lowest at all applied fields for pristine MgB2 and the sample doped with 3 wt % nD gives the best J(c) values at all fields. These results are discussed in terms of extrinsic pinning due to dispersed n-diamond in the host MgB2 matrix along with the intrinsic pinning due to possible substitution of C at boron site and increased interband scattering for highly doped samples resulting in extraordinary performance of the doped system.