Purpose: The purpose of this study was to understand the perceived benefits and clinical utility of cardiopulmonary exercise testing (CPET) from the perspectives of physiotherapists and patients and to explore the factors that influence adopting CPET in a stroke rehabilitation setting. Method: A qualitative descriptive study was conducted. Physiotherapists ( n = 6) participated in a focus group to discuss the use of CPET in practice. Patients ( n = 8) who had completed CPET during stroke rehabilitation participated in a semi-structured interview to explore their experiences. Thematic analysis was performed. Results: CPET increased the physiotherapists’ confidence in prescribing exercise, especially for medically complex patients. Ongoing medical management early post-stroke was a barrier to referral. Physiotherapists expressed decreased confidence in interpreting test results. Consultation with local experts facilitated the use of CPET. Patients described how CPET increased their confidence to participate in exercise. They desired more information before and after CPET to better understand the purpose and results and their relation to their rehabilitation goals. Conclusions: Both physiotherapists and patients described the benefit of having CPET available to support them as they participated in exercise in a stroke rehabilitation setting. Physiotherapists would benefit from having educational tools to support their interpretation and application of test results, and patients would benefit from improved communication and education to support their understanding of the relevance of CPET to their rehabilitation goals. Future research should explore these findings in other stroke rehabilitation settings.