Although inappropriate gestational weight gain is considered closely related to adverse maternal and birth outcomes globally, little evidence was found in low- and middle-income countries. Study Objectives. This study is aimed at identifying the determinants of gestational weight gain and examine the association between gestational weight gain and maternal and birth outcomes in the Northern Region of Ghana. Study Methods. The study used a facility-based cross-sectional study design involving 611 antenatal and delivery records in Tatale district, Tamale west, and Gushegu municipal hospitals. A two-stage sampling method involving cluster and simple random sampling was employed. Descriptive statistical analysis and measures of central tendency were used to describe the sample. The multinomial logistic regression model was used to determine the determinants of gestational weight gain and its association with maternal and birth outcomes. Among the 611 women included in the study, 516 (84.45%) had inadequate gestational weight gain, and 19 (3.11%) had excessive gestational weight gain. The gestational weight gain ranged from 2 kg to 25 kg with a mean of 7.26 ± 3.70 kg. The risk factor for inadequate gestational weight gain was low prepregnancy BMI (adjusted odds ratio (AOR) = 1.33, 95% CI = 1.18 - 2.57, P = 0.002). Pregnant women who had inadequate gestational weight gain were significantly less likely to deliver through caesarean section (AOR = 0.27, 95% CI = 0.12 - 0.61, P = 0.002), and those who had excessive weight gain were more likely to undergo caesarean section (AOR = 19.81, 95% CI = 5.38 - 72.91, P = 0.001). The odds of premature delivery (birth < 37 weeks) among pregnant women with inadequate weight gain were 2.88 (95% CI = 1.27 - 6.50, P = 0.011). Furthermore, subjects who had excessive weight gain were 43.80 times more likely to give birth to babies with macrosomia (95% CI = 7.07 - 271.23, P = 0.001). Inappropriate gestational weight gain is prevalent in Ghana, which is associated with caesarean section, preterm delivery, delivery complications, and macrosomia. Urgent policy interventions are needed to improve on the frequent monitoring and management of gestational weight gain of pregnant women till term.