Background <p>Previous studies have examined the associations between individual foods or nutrients, but few studies have considered dietary patterns associated with ovarian cancer (OC) survival.</p> Methods <p>In a prospective cohort study, we examined the association between pre-diagnosis and post-diagnosis overall diet, including changes from pre-diagnosis to post-diagnosis, and overall survival (OS) in 560 patients with OC. Dietary intake was collected using a valid 111-item food frequency questionnaire. Principal component analysis was performed to determine the dietary patterns. Cox proportional hazard regression models were used to assess the hazard ratio (HRs) and 95% confidence interval (CIs).</p> Results <p>Two dietary patterns were identified: Balanced and nutritious pattern and Energy-dense pattern. The highest tertile of the post-diagnosis Balanced and nutritious pattern scores was related to better OS compared with the lowest tertile (HR = 0.40, 95% CI = 0.17–0.95, <i>P</i>_trend &lt; 0.05). However, no significant association between pre-diagnosis and post-diagnosis Energy-dense pattern scores and OS was observed. Compared to those who had persistently high Balanced and nutritious pattern scores, patients who changed from a high score of pre-diagnosis Balanced and nutritious pattern to low post-diagnosis, as well as those who shifted from a low to a high score, both had a decreased OS (HR_{high−low vs. high−high} = 1.91, 95% CI = 1.18–3.08; HR_{low−high vs. high−high} = 2.19, 95% CI = 1.24–3.86). Additionally, patients who changed from a high pre-diagnosis score to a low post-diagnosis score had a decreased OS compared to those with consistently low Energy-dense pattern scores (HR_{high−low vs. low−low} = 1.74, 95% CI = 1.06–2.84).</p> Conclusions <p>Greater adherence to the Balanced and nutritious pattern as well as less adherence to the Energy-dense pattern from pre-diagnosis to post-diagnosis were associated with better OC survival.</p>