Within Canada, the need for individuals with science, technology, engineering, and mathematics (STEM) skills has been well documented. One tactic towards increasing the number of individuals with STEM skills is to focus on the kindergarten to grade 12 (K-12) STEM education stakeholders, who can directly and/or indirectly influence a student's STEM education trajectory. One of those stakeholders is K-12 STEM outreach units (SOUs). The purpose of this research was to contribute to the STEM education literature in Canada by identifying the landscape of university-based K-12 SOUs and exploring their organizational features (mission, target audience, stakeholders, initiatives, capacity, resources, and partnerships). This study used an explanatory two-phase approach involving quantitative and qualitative data collection and analysis. Phase 1 was an environmental scan of university-based SOUs websites. Phase 2 consisted of an online survey designed to further explore SOUs' organizational features. The findings from this study suggest commonality in SOUs' mission and intentionality towards engaging youth, including those underrepresented and underserviced in STEM fields such as Black youth, Indigenous youth, racialized youth, youth from low socio-economic communities, and girls. However, the findings indicate a large variability of other organizational features such as their size, operating budget, and the number of partnerships. Overall, the findings affirm that university-based SOUs have a role to play in the K-12 STEM learning ecosystem, helping students develop STEM knowledge and skills.