Background In the Netherlands, a maximum waiting time from diagnosis to treatment (WT) of 5 weeks is recommended for curative cancer treatment. This study aimed to evaluate the association between WT and overall survival (OS) in patients undergoing gastrectomy for cancer. Methods This nationwide study included data from patients diagnosed with curable gastric adenocarcinoma between 2005 and 2014 from the Netherlands Cancer Registry. Patients were divided into two groups: patients who received neoadjuvant therapy followed by gastrectomy, or patients who underwent gastrectomy as primary surgery. WT was analyzed as a categorical (≤5 weeks [Reference], 5–8 weeks, >8 weeks) and as a discrete variable. Multivariable Cox regression analysis was used to assess the influence of WT on OS. Results Among 3778 patients, 1701 received neoadjuvant chemotherapy followed by gastrectomy, and 2077 underwent primary gastrectomy. In the neoadjuvant group, median WT to neoadjuvant treatment was 4.6 weeks (interquartile range [IQR] 3.4–6.0), and median OS was 32 months. In the surgery group, median WT to surgery was 6.0 weeks (IQR 4.3–8.4), and median OS was 25 months. For both groups, WT did not influence OS (neoadjuvant: 5–8 weeks, hazard ratio [HR] 0.82, p = 0.068; >8 weeks, HR 0.85, p = 0.354; each additional week WT, HR 0.96, p = 0.078; surgery: 5–8 weeks, HR 0.91, p = 0.175; >8 weeks, HR 0.92, p = 0.314; each additional week WT, HR 0.99, p = 0.264). Conclusions Longer WT until the start of curative treatment for gastric cancer is not associated with worse OS. These results could help to put WT into perspective as indicator of quality of care and reassure patients with gastric cancer.