Modifications in the processing of information relevant to oneself have been reported in breast cancer (BC) patients. Here, we characterize the longitudinal changes to self‐representations in BC patients and how they are related to intrinsic functional brain connectivity. We tested 16 BC patients before (T1) and 1 year after the end of chemotherapy (T2) along with 24 healthy control participants (HC) at similar time points. Participants underwent resting‐state fMRI and completed the Questionnaire of Self‐Representation (QSR), which evaluates self‐assertion and self‐esteem. Resting‐state functional connectivity (RSFC) was calculated for regions implicated in self‐referential processes (dorsomedial prefrontal cortex dmPFC, posterior cingulate cortex PCC, and dorsal anterior cingulate cortex dACC) and correlated with QSR scores. QSR scores were on average larger in patients compared with HC and did not vary over time. RSFC between the dACC and regions supporting body awareness (precentral/postcentral and supramarginal gyri, superior parietal lobule) decreased more between T1 and T2 in BC patients than in HC. BC patients had lower RSFC than HC between the dmPFC and the PCC, and regions supporting mental imagery (precuneus, lingual gyrus), at each time point, and a greater decrease from T1 and T2. QSR scores negatively correlated with RSFC. Patients described themselves as having greater self‐awareness and positive self‐image, reflecting a fighting spirit. In parallel, patients presented a decrease in cortical activity related to body awareness and mental imagery of self‐representations over time that may be related to the positive self‐image patients have and could reflect a temporary adaptive strategy.