© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. Purpose: Evidence suggests that partners of men with prostate cancer (CaP) experience greater psychosocial distress compared with men themselves. However, the experiences of partners of high-risk (1 in 4) Black African (BA) and Black Caribbean (BC) men with CaP remain poorly understood as existing research has predominantly focused on Caucasian populations. This study aimed to address this gap by exploring partners’ experience and support needs as influenced both by the specific impacts of CaP, treatment side effects and socio-cultural context. Methods: Using a constructivist grounded theory approach, eight face-to-face, two Skype and one telephone interviews were conducted with eligible partners (n = 11). The interviews were analysed using constant comparison following key stages of open, focused and theoretical coding. Results: Three broad categories emerged which described participants’ experiences: ‘partner in the passenger seat’, ‘care-giving on an isolating journey’, and ‘coping as a partner’. Findings showed that BA and BC cultural marital context influenced how partners experienced and traversed the CaP journey. Peripheral involvement in decision-making, communication restrictions, limited access to support and lack of recognition for their experiences and needs further contributed to partners’ psychological and emotional distress. Conclusions: Cultural beliefs, behaviours and values should be taken into account when developing psychosocial support for partners and their men with CaP. Specifically providing information focused on partners and including them in the CaP care pathway could help ensure that partners’ needs are recognised and improve marital communications. This could potentially help partners and their men to identify acceptable ways of supporting each other throughout the CaP experience.