Background As the population ages, the impact of increasing patient age on surgical outcomes needs to be better elucidated. This study aimed to conduct a detailed evaluation of the impact of patient age on general surgery outcomes. Methods Emergency and elective admissions under general surgery services at two hospitals in South Australia between 2017 and 2023 were included. Regression models were performed for the predictor of age, adjusted for confounders of sex and admission type. Outcomes included length of hospital stay, in-hospital mortality, surgical complications, and complication grade. For each outcome, three models were performed, examining continuous age, comparing below and over 18 years of age, age in 10-year categories. Results 43,633 general surgery admissions were included. For each 10-year increase in patient age, mean length of hospital stay increased by 14% (mean ratio 1.14, 95%CI 1.13–1.14), odds of in-hospital mortality more than doubled (odds ratio 2.07, 95%CI 1.91–2.24), odds of experiencing a complication increased by 25% (odds ratio 1.25, 95%CI 1.23–1.26), and odds of experiencing a higher complication grade increased by 10% (odds ratio 1.10, 95%CI 1.08–1.12). Each 10-year age category was a statistically significant predictor of length of hospital stay (p<0.0001), in-hospital mortality (p<0.0001), presence of complications (p<0.0001), and complication grade (p<0.0001). Conclusions Not only is patient age strongly associated with general surgery outcomes, but outcomes incrementally worsen as patient age increases. Going forward as the population ages, surgical systems of care should further integrate patient age within clinical decision-making and future research.