The competition in the biopharmaceutical market is increasing due to the market entry of biosimilars and rising costs in research and development (R&D) of new drugs. Hence, continuous manufacturing gained significant attention due to its potential in reducing production cycle times and costs, as well as the possibility of real-time release testing (RTRT). As a consequence, active monitoring and/or control systems are required for product quality measurements and in-process control. Process analytical technology (PAT) emerged as a robust strategy for the development and implementation of adaptive controls, instead of fixed controls (i.e., batch testing of end product). Several relevant applications of PAT were developed in recent years aimed at implementing continuous monitoring and/or control for the purification of monoclonal antibodies (mAbs). Through the evaluation of state-of-the-art applications this review highlights future opportunities in the field of quantitative real-time analytical techniques for the characterization of mAbs in continuous downstream biomanufacturing.