The present research focuses on investigating the magneto-nanofluidic convection within a circular grooved cavity, featuring an adiabatic central obstruction of fixed size. The cavity incorporates a partially placed heating element along its circular periphery considering the length being equal to the width of the cavity. Utilizing CuO–H2O nanofluid, the study employs systematic numerical simulations to assess the thermal-fluid behavior concerning Reynolds number (Re), Rayleigh numbers (Ra), and Hartmann number (Ha). The nanofluid is introduced through a cold inlet at the top left and exits through a top right outlet. By examining the effects of viscosity on fluid buoyancy through varying Re and Ra, and studying different Ha values for the introduction of a horizontal magnetic field, the research gains valuable insights. The comprehensive parametric analysis of Ra, Re, and Ha sheds light on intricate convective phenomena in such geometries with consideration of multi-physical scenarios. Additionally, it is observed that the utilization of nanofluid facilitates maximum heat transport rate.