Objective To assess the decision‐making process in fit and frail older breast cancer patients. Methods Breast cancer patients aged ≥70 years who completed the G8 frailty screening tool (G8) were included in this retrospective study. Socio‐demographic and clinical characteristics were collected, as well as information from geriatric assessment (GA). Treatment decisions were compared with national guidelines. Results Of 177 patients, 85 patients were considered fit by the G8 (G8‐fit) and 92 patients frail (G8‐frail). All G8‐fit and 53 G8‐frail were proposed for surgery. GA was performed in 34 patients (9 G8‐fit; 25 G8‐frail) of whom 16 (2 G8‐fit;14 G8‐frail) were considered frail (GA‐frail). 28 out of these 34 patients were considered fit for surgery (including 11 GA‐frail); their impairments were unlikely to interfere with surgery or life expectancy. Reasons for adjusting treatment were physical/cognitive condition and patient preference. Ultimately, 123 patients underwent surgery in accordance with guidelines (81 G8‐fit;42 G8‐frail, p < 0.001). Survival was reduced in G8‐frail compared to G8‐fit (p = 0.001), but G8 lost its association with mortality in multivariable survival analysis. Among patients undergoing surgery, no difference in mortality was seen between G8‐fit and G8‐frail (p = 0.996). Conclusion The G8 is associated with treatment decisions and did not affect survival in patients undergoing surgery. In the decision‐making process, the G8 may help and estimates the need for adaptive care.