Insufficient physical activity (PA) is a critical public health issue especially in the context of COVID-related deconditioning. Health professionals are well placed to promote community-based PA but there is little supporting implementation research. We aimed to explore physiotherapists’ knowledge, views, attitudes and experiences regarding the promotion of physical activity, exercise and sport within daily clinical practice in order to guide development of strategies to support implementation of PA promotion by physiotherapists, in particular those treating older people, and adults and children with a disability. We conducted interviews and focus groups with 39 physiotherapists. Two researchers coded transcripts with an iterative coding approach. Analysis returned five main themes: putting principles into practice; working with conflicting priorities; multiple client barriers; connections build confidence; and the battle for information. The physiotherapists accepted their legitimate role in PA promotion. Limited clinical and administrative time and acute treatment priorities often superseded PA promotion but the lack of updated information regarding suitable community-based PA opportunities and lack of trust in community providers were the biggest barriers. Strategies to enhance PA promotion by physiotherapists should address time and information constraints, and build partnership connections between health professionals and community-based PA providers.