Objectives: While the association between pregestational obesity and perinatal complications has been established, it is necessary to update the current understanding of its impact on maternal and foetal health due to its growing prevalence. Thus, this study aimed to investigate the association between pregestational obesity with the leading perinatal complications during the last 6 years. Study design: A cross-sectional study was performed in San Felipe, Chile. Anonymised data of 11,197 deliveries that occurred between 2015 and 2021 were included. Methods: Pregestational body mass index was defined according to the World Health Organisation during the first trimester of pregnancy. The association between pregestational obesity and perinatal complications was analysed by calculating the odds ratio (OR), which was adjusted for confounding variables. Statistical differences were considered with a P-value of <0.05. Results: The prevalence of pregestational obesity was 30.1%. Pregestational obesity was related to a high incidence of perinatal complications (≥3 complications; P < 0.0001). The main perinatal complications were caesarean section, large for gestational age (LGA), gestational diabetes (GD), macrosomia, hypertensive disorders of pregnancy (HDP), premature rupture of membranes (PROM), intrauterine growth restriction, and failed induction. Pregestational obesity was shown to be a risk factor for macrosomia (OR: 2.3 [95% confidence interval {95% CI}: 2.0–2.8]), GD (OR: 1.9 [95% CI: 1.6–2.1]), HDP (OR: 1.8 [95% CI: 1.5–2.1]), LGA (OR: 1.6 [95% CI: 1.5–1.8]), failed induction (OR: 1.4 [95% CI: 1.0–1.8]), PROM (OR: 1.3 [95% CI: 1.1–1.6]), and caesarean section (OR: 1.3 [95% CI: 1.2–1.4]). Conclusions: Pregestational obesity has been shown to be a critical risk factor for the main perinatal complications in the study population. Pregestational advice is imperative not only in preventing pregestational obesity but also in the mitigation of critical perinatal complications once they arise.