BACKGROUND: The RUBY randomised controlled trial was found to be effective in promoting breastfeeding continuation, in the setting of a high income country, through a program of proactive telephone-based peer support in the first 6 months postpartum. This paper explores women's experiences of receiving the peer support intervention in the RUBY trial. METHODS: Ten in-depth, face-to-face interviews were conducted between December 2015 and November 2016 in Metropolitan Melbourne, and regional Victoria, Australia. Participants were women who received the peer support intervention in the RUBY trial and were between 11 and 15 months postpartum at the time of interview. Interviews were underpinned by social support theories and were analysed using inductive thematic analysis. RESULTS: A global theme of 'non-judgemental support and guidance' was identified, which included five organising themes. Four of the organising themes centred on the support from the peer, in which women felt the support was a 'positive experience with empathy and understanding', 'non-judgemental', 'practical advice', and a 'social connection that was more than just breastfeeding'. In contrast to the support from peers was the theme 'not all support from family and friends is supportive'. CONCLUSION: Participants, including those who considered that they had adequate and available family and friend support for breastfeeding, valued and appreciated the non-judgemental, empathetic and understanding support from peers. This support, facilitated by the anonymity of the telephone-based program, allowed open and honest conversations, normalising women's experiences and helping them feel less alone in their challenges with breastfeeding and transition to motherhood. These findings can inform the design, and upscaling, of innovative and sustainable peer support models, ensuring delivery of effective and engaging support with a broad population reach.