The aims were to examine changes in patient-reported outcome measures (PROMs), level of physical activity (LPA), and physical capacity from before to after an outpatient rehabilitation program (ORP) for women with breast cancer (BC). Further aims were to explore the proportions of patients with clinically relevant improvements defined as ≥ 10% beneficial change in the scores of PROMs and variables associated with such improvements.A total of 270 women within working age (< 67 years) who recently (< 1.5 years) had completed primary therapy for BC with curative intent were included. The ORP consisted of seven weekly group sessions with patient education, group conversations, and PA. The patients completed questionnaires measuring health-related quality of life (HRQoL), fatigue and LPA before (T0), immediately after (T1), and 6 months after (T2) the program, and were physically tested at T0 and T1. The mean age of the patients was 50.4 years (SD 7.3) and the mean time since diagnosis was 10.6 months (SD 2.6). All patients had undergone surgery and 94% radiotherapy, and 96% had received chemotherapy and/or hormonal therapy.Physical-, role-, emotional-, cognitive-, and social function, global health, and fatigue significantly improved from T0 to T1. Physical-, role-, and cognitive function, and fatigue significantly improved from T1 to T2. LPA and physical capacity significantly improved from T0 to T1. More than 40% of the patients had a clinically relevant improvement in role-, social function, and fatigue symptoms, from T0 to T1. Low level of education was associated with an improvement in emotional function, and living alone was associated with an improvement in mental fatigue.HRQoL, fatigue, LPA, and physical capacity improved in women within working age recently treated for BC who participated in an ORP.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13187-022-02211-6.