Breast cancer treatment often involves drugs with significant cardiotoxicity. One of the novel approaches to preventing and managing heart failure and reduced exercise tolerance in patients with breast cancer is cardio-oncology rehabilitation. A submaximal exercise test allows for the assessment of physical load tolerance and the effectiveness of rehabilitation programs. The aim of this review was to evaluate the feasibility of using the six-minute walk test for prescribing and assessing the effectiveness of cardiac training programs in patients with breast cancer through the analysis of randomized clinical trials. The six-minute walk test has demonstrated reliability and validity when performed in oncology patients, although its results may be influenced by numerous factors. The maximum heart rate obtained during the six-minute walk test can be used to determine training intensity, and the test results can assess the effectiveness of rehabilitation programs. Changes in health status can be monitored using treadmill testing, while wearable medical devices enable the use of the six-minute walk test in remote rehabilitation. Actual testing is necessary to determine exercise tolerance: the six-minute walk test can be utilized for dynamic monitoring of patients’ health both in conventional settings and on a treadmill.