This study aimed to evaluate the changes in post-diagnosis dietary intake of breast cancer survivors. A total of 112 participants from the Malaysian Breast Cancer Survivorship Cohort study with dietary intake at one-year post-diagnosis (T1) and three-year post-diagnosis (T2) were included. A three-day food record was used to assess the dietary intake of breast cancer survivors. The participants' anthropometrical measurements were measured at both time points (n = 95). Notably, we found that around half of the participants were obese at both time points. Body weight and body mass index increased significantly between the two time points (P < 0.01). Most of the participants did not meet the Malaysian recommended nutrient intake for dietary fat, fiber, and calcium at both time points. The energy intake significantly decreased (from 1,596 kcal/day to 1,524 kcal/day, P = 0.028) within the survivors. Significant decreases were observed in the overall intakes of carbohydrates, total sugar, protein, fiber, and calcium (P < 0.05). Overall, many Malaysian breast cancer survivors remained overweight or obese and had suboptimal dietary intake even at three years post-diagnosis. These require more proactive dietary intervention with continuous monitoring and evaluation among breast cancer survivors for their survivorship care.