The impact of living with metastatic breast cancer (MBC) is considerable and psychosocial support can be beneficial. Mindfulness-based stress reduction (MBSR) can help self-management of anxiety, depression, quality of life (QoL), and fatigue and has been evaluated in early-stage breast cancer but not MBC. This study investigated the acceptability and feasibility of providing MBSR for women with MBC and of introducing MBSR into a National Health Service (NHS) setting. A mixed methods convergent design was used. Eligible women with MBC, an Eastern Cooperative Oncology Group (ECOG) score of 0 to 2, stable disease, and life expectancy of at least 6 months were invited to attend (by their oncologist) an 8-week MBSR course. Qualitative interviews with patients, a focus group, and interview with NHS staff were held to explore acceptability and feasibility of MBSR. Questionnaires at baseline, during (weeks 4, 8), and after (weeks 16, 24) the course measured fatigue, anxiety and depression, mindfulness, disease-specific QoL, and generic preference based QoL. Of 100 women approached, 20 joined the study. One woman dropped out prior to the intervention due to illness progression. Nineteen women took part in 3 MBSR courses. Recruitment to 2 of the 3 courses was slow. Commitment to 8 weeks was a reason for non-participation, and proved challenging to participants during the course. Participants found the course acceptable and reported many cumulative and ongoing benefits. These included feeling less reactive to emotional distress and more accepting of the disruption to life that occurs with living with MBC. There was high attendance, completion of course sessions, adherence to home practice, excellent follow-up rates, and high questionnaire return rates. MBSR was acceptable to MBC patients, who perceived benefits such as improved anxiety and QoL; but the MBSR course requires a considerable time commitment. There is scope to tailor the intervention so that it is less intensive.