Social support can be facilitated through exercise programs for people living with cancer, but there is limited research on how best to foster it in online exercise oncology classes. This study examined current training that fitness professionals receive on the provision and facilitation of social support, experiences people living with cancer have with social support, and supportive behaviours and barriers for providing and obtaining support in online group exercise oncology programs in Calgary, Alberta, Canada. Guided by interpretive description methodology, training materials were reviewed, observations of fitness professional training and online exercise classes (n = 10) were conducted, and adults living with and beyond cancer (n = 19) and fitness professionals (n = 15) were interviewed. These data were collected from January 2021 to June 2021. Analysis of the data collected resulted in the identification of three themes: Creating a welcoming environment, helping improve exercise ability and reach goals, and learning to provide and facilitate support online. A catalogue of supportive behaviours that can help to provide and facilitate and barriers that can hinder the provision and obtaining of social support in exercise oncology classes is presented. The findings provide guidance when structuring online classes and inform developing strategies for fitness professionals to use in online classes to foster social support by considering the wants and needs of participants, facilitating support between participants with similar experiences and interests, and integrating support into physical activity.