This book gathers a selection of papers presented at ROBOT 2019 - the Fourth Iberian Robotics Conference, held in Porto, Portugal, on November 20th-22nd, 2019. ROBOT 2019 is part of a series of conferences jointly organized by the SPR - Sociedade Portuguesa de Robótica (Portuguese Society for Robotics) and SEIDROB - Sociedad Española para la Investigación y Desarrollo en Robótica (Spanish Society for Research and Development in Robotics). ROBOT 2019 built upon several previous successful events, including three biannual workshops and the three previous installments of the Iberian Robotics Conference, and chiefly focused on presenting the latest findings and applications in robotics from the Iberian Peninsula, although the event was also open to research and researchers from other countries. The event featured five plenary talks on state-of-the-art topics and 16 special sessions, plus a main/general robotics track. In total, after a stringent review process,112 high-quality papers written by authors from 24 countries were selected for publication.