The 21st International Conference on Ubiquitous Robots (UR 2024) will be held at the Kimmel Center for University Life in NYU, Manhattan, New York, USA, from June 24 to 27, 2024. Since its inception in 2004, Ubiquitous Robots has now established itself as a leading mid-size robotics conference, bringing together robotics researchers from around the world who share the vision that robots, smartphones, will become ubiquitous in our daily lives, and help connect and empower humans. Robotics is the ultimate interdisciplinary field, and Ubiquitous Robots invites contributions from the entire foundational spectrum—design, perception, manipulation, interfaces, mobility, intelligence—and application domains—industrial, social, transportation, medical, rehabilitation, healthcare, agriculture, construction, security, disaster, and many others. Ubiquitous Robots 2024 promises to be an exciting and innovative event, with invited talks, oral and poster presentations, workshops, and other new formats that will engage participants. We invite you to submit your latest work to Ubiquitous Robots 2024, and to come experience the myriad attractions of New York.