Objective This study aims to evaluate perinatal outcomes, according to gestational weight gain (GWG) in obese women. Study Design A retrospective cohort of perinatal outcomes in obese women who gained below, within, or above the 2009 Institute of Medicine guidelines and delivered ≥ 36 weeks. Additionally, outcomes, according to the rate of GWG (kg/week; minimal [< 0.16], moderate [0.16-0.49], or excessive [> 0.49]) were compared among women delivering preterm. Results Overall, 5,651 obese women delivered ≥ 36 weeks. GWG above guidelines was associated with increased cesarean section (adjusted odds ratio [aOR]: 1.44, 95% confidence interval [CI]: 1.21-1.72), gestational hypertension (aOR: 1.58, 95% CI: 1.21-2.06), and macrosomia (birth weight ≥ 4,000 g) (aOR: 2.08, 95% CI: 1.62-2.67). GWG below recommendations was associated with less large for gestational age infants (aOR: 0.60, 95% CI: 0.47-0.75). A total of 6,663 women delivered ≥ 20 weeks. Minimal weekly GWG was associated with increased spontaneous preterm birth (aOR: 1.56, 95% CI: 1.23-1.98) and more small for gestational age (SGA) infants (aOR: 1.55, 95% CI: 1.19-2.01). Excessive weekly GWG was associated with increased indicated preterm birth (aOR: 1.61, 95% CI: 1.29-2.01), cesarean section (aOR: 1.39, 95% CI: 1.20-1.61), preeclampsia (aOR: 1.83, 95% CI: 1.49-2.26), neonatal intensive care unit admission (aOR: 1.33, 95% CI: 1.08-1.63), and macrosomia (aOR: 2.40, 95% CI: 1.94-2.96). Conclusions Obese women with excessive GWG had worse outcomes than women with GWG within recommendations. Limited GWG was associated with increased spontaneous preterm birth and SGA infants.