Abstract Objectives Treatment delay can adversely affect cancer prognosis and public health. However, previous studies have not examined the association between cancer treatment delay and 5-year mortality risk for various cancer types in a single study population. Methods We used retrospective cohort data from 21 740 patients diagnosed with common cancers between 2000 and 2017, with mortality follow-up to 2022, from the Philippines’ Department of Health-Rizal Cancer Registry to understand how treatment delay of <30, 30–90, or >90 days was associated with 5-year all-cause mortality risk, by cancer type and stage at diagnosis. Poisson regression with robust variance was used to obtain the risk ratio and 95% confidence interval for the associations. Results After adjusting for confounding, patients with treatment delays of more than 90 days had significantly higher 5-year mortality risk (risk ratio = 1.09; 95% confidence interval: 1.04–1.14) compared to those with delays of <30 days. Treatment delay was significantly associated with higher 5-year mortality in breast and cervical cancers, but not for the other cancer types (P-trend < .05). There was also a significant association between treatment delay and 5-year mortality of non-metastatic but not metastatic cancer at diagnosis (P-trend < .05). Conclusion Our findings suggest that the 5-year prognosis of certain cancer types and non-metastatic cancer may be more adversely influenced by their delayed treatment, which will inform cancer control programs globally to reduce treatment delay and improve cancer prognosis.