Background As future health care leaders who work and train in diverse clinical settings, resident physicians are uniquely positioned to advance sustainable health care systems. However, residents are insufficiently educated about health care sustainability and given limited opportunities to engage in planetary health. Objective This article introduces and reports on the early outcomes of the Trainee-Led Research and Audit for Sustainability in Healthcare Canada (TRASH-CAN), a resident-driven initiative launched in 2023 with the aim of reducing Canadian health care's environmental impact. Methods In 2023-2024, we developed a web-based platform that facilitates trainee-led action to support the promotion of sustainability literature, collaboration with national and international institutions, and execution of quality improvement projects to reduce health care waste under the 3 brand pillars of Learning, Leadership, and Delivery. We have promoted TRASH-CAN and its website through conference presentations, social media, mailing lists, and word of mouth. These activities support our goals of engaging trainees, pairing them with mentors, and initiating a variety of quality improvement projects focused on planetary health. Results In its first year of operation, TRASH-CAN has developed a fully functional website hosting intake forms and detailing ongoing projects and opportunities. We have enrolled 15 faculty mentors and 16 residents and medical students, with ongoing projects such as transitioning hospitals to reusable alternatives and optimizing procedural custom operating room equipment packs. Conclusions TRASH-CAN's inaugural year has led to the initiation of 11 sustainability projects and the enrollment of 31 faculty mentors and trainees.