In-situ cutting transport measurement is essential to understand the hydrodynamics and operational parameters required for efficient annulus cleaning. Electrical resistance tomography (ERT) has been a promising method in many industrial applications. This study aimed to provide comprehensive information on the use of a non-invasive ERT method to examine the volume fraction of solids in the presence of non-Newtonian fluid (0.5 wt percent of Flowzan) in a directional drilling annulus (80–90° from vertical orientation). The experiments were performed in a horizontal flow loop system where the annulus segment was 240 (6.16 m) inch long with an inner and outer diameter of 2.5 inches (6.4 cm) and 4.5 inches (11.4 cm), respectively. The results obtained indicated that the ERT device could effectively detect the volume fraction of the solids in the presence of non-Newtonian fluid (Flowzan) under different drilling conditions. Results also showed that the annulus’ successful cleaning was observed with an increase in fluid mass flow rates indicated the relative increase in cuttings volumes (AVF = 7 to 9%). Besides, the rotation of the drill pipe often had a beneficial effect on cutting transport. Furthermore, it was observed that both (30%) eccentricity and inclination (80–85 °) cause a reduction in cutting volume fraction. Therefore, this study will provide an avenue for the industrial implementation of in situ ERT measurement technology in directional drilling operations, particularly in the case of non-Newtonian drilling fluids.