Biologics manufacturing requires the clearance of Host Cell Proteins (HCPs) from recombinant therapeutic protein to acceptable low levels to ensure product purity and patient safety. To ensure adequate removal, a highly sensitive method, commonly in the form of Enzyme-Linked Immunosorbent Assay (ELISA), is necessary to quantify the HCPs amount in process intermediates and drug substance. We report the development of a chemiluminescent detection based ELISA (luminescent ELISA) in lieu of previously used colorimetric method (colorimetric ELISA) to improve assay sensitivity for the quantification of Chinese Hamster Ovary (CHO) HCPs in a monoclonal antibody product (mAb-A). For luminescent ELISA, Pierce Supersignal ELISA Femto was chosen as the substrate to replace colorimetric substrate TMB. The assay performance of luminescent and colorimetric ELISA was directly compared side-by-side. Our data show that luminescent ELISA has better signal/background ratio, broader linear range over logarithmic scales, and better linearity within the same linear range than colorimetric ELISA. Luminescent ELISA also demonstrates better lowend linearity, greater accuracy and precision. In addition, the Limit of Detection (LOD) and Limit of Quantification (LOQ) are significantly improved with luminescent ELISA as compared to colorimetric ELISA. In summary, luminescent ELISA is a more sensitive method and demonstrates superiority over colorimetric method for CHO HCP quantification.