Drilling fluid additives play a vital role in modifying the drilling fluid properties for the ease of drilling operations in oil and gas wells. In this work, two different drilling fluid additives such as titanium oxide nanoparticles and a hydrophobically modified associative polymer were employed to develop several drilling fluid formulations. Various drilling fluid formulations were made by varying the concentrations of the nanoparticles and polymer to study the theology, filtration, and shale inhibition properties. Rheological and filtration properties of the drilling fluid formulation were determined to study the performance of drilling fluid formulations. TEM analysis of drilling fluid was carried out to study the interactions and distribution of drilling fluid additives. SEM analysis of shale was performed to investigate the surface texture and distribution of additives on the shale surface. Shale inhibition characteristics were evaluated by performing hot rolling dispersion and linear swelling tests of shale. Experimental results exhibited that the addition of nanoparticles and the polymer enhanced rheological properties and reduced fluid loss. However, the synergistic effect of the nanoparticles and polymer was far more prominent on rheological and filtration properties. TEM analysis of drilling fluid formulations revealed the homogenous distribution additives in the drilling fluids. A SEM analysis of shale surfaces after the hot rolling test disclosed that nanoparticles plugged the micropores and covered the defects in the shale surface. A hot rolling dispersion test showed that the dispersion of shale was reduced by the addition of nanoparticles and the polymer in the drilling fluid formulation. The minimum dispersion and least swelling of shale were observed with the formulation containing both nanoparticles and the polymer. Therefore, based on shale inhibition results, the titania nanoparticles and associative polymer can be used as potential additives for drilling fluids.