The competition in the biopharmaceutical market is increasing due to the market entry of biosimilars and rising costs in research and development 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. As a consequence, active monitoring and/or control systems are required for quantitative product quality measurements and in-process control. Process analytical technology emerged as a robust strategy for the development and implementation of in situ real-time testing, instead of the standard batch testing of end product. 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 monoclonal antibodies in continuous downstream biomanufacturing.