The first AAAI workshop on Machine Learning for Operations Research (ML4OR), co-organized by Ferdinando Fioretto (Syracuse University), Emma Frejinger (Universite de Montreal), Elias B. Khalil (University of Toronto), and Pashootan Vaezipoor (University of Toronto), involved more than 100 attendees and speakers who convened to present cutting-edge research at the intersection of learning and decision-making. We hope that the momentum in this emerging area will continue for years to come, at AAAI and other AI/ML conferences! Our invited speakers covered a broad range of exciting developments spanning new theoretical results for machine learning in integer programming by Dr Ellen Vitercik (UC Berkeley), foundational insights into the use of graph neural networks in combinatorial algorithms by Professor Stefanie Jegelka (MIT), late-breaking results on evaluating and comparing algorithms by Professor Kevin Leyton-Brown (UBC), and a survey of the use of deep learning in engineering optimization problems by Professor Pascal Van Hentenryck (Georgia Tech). Accepted papers to the workshop (available on the website) were also presented and spanned authors from universities in five continents and on topic as diverse as aircraft scheduling and battery management, all operations research problems where machine learning is starting to make an impact! The first AAAI workshop on Machine Learning for Operations Research (ML4OR), co-organized by Ferdinando Fioretto (Syracuse University), Emma Frejinger (Universite de Montreal), Elias B. Khalil (University of Toronto), and Pashootan Vaezipoor (University of Toronto), involved more than 100 attendees and speakers who convened to present cutting-edge research at the intersection of learning and decision-making.