Purpose <p>To evaluate the implementation fidelity of a blended intervention aimed at optimizing physical recovery following gastrointestinal or lung cancer surgery, involving patients, dietitians, and physiotherapist.</p> Methods <p>Implementation fidelity was evaluated alongside a Randomized Controlled Trial (RCT) investigating the effect of the Optimal Physical Recovery After Hospitalization (OPRAH) intervention. For three months post-discharge, dietitians and physiotherapists remotely coached patients using data on physical activity and protein intake collected via a smartphone application and activity tracker. Carroll’s framework guided the evaluation of the intervention using both quantitative and qualitative data.</p> Results <p>Patient adherence to wearing the activity tracker and monitoring protein intake was high. All patients received coaching from at least one of the two allied healthcare professionals. The frequency of coaching varied between patient populations, with the highest frequency for patients after gastrointestinal surgery. A negative moderating factor was that the OPRAH intervention was difficult to implement in the daily work routine. Positive moderating factors included positive responsiveness of physiotherapists, dietitians, and patients, well-functioning technology, and facilitation strategies that effectively engaged physiotherapists and dietitians.</p> Conclusions <p>As adherence to the intervention was high, the observed effects of the RCT can be more confidently attributed to the OPRAH intervention. The main challenge for long-term implementation is integrating the intervention into routine clinical practice.</p> Implications for Cancer Survivors <p>OPRAH can support cancer survivors during a vulnerable phase of recovery, with the potential to improve physical outcomes. Sustainable implementation requires embedding the intervention into standard care and maintaining close collaboration among healthcare providers.</p>