PURPOSE: This study aimed to identify psychosocial predictors of inadequate and excessive gestational weight gain among Korean pregnant women. METHODS: Data were collected through an online survey of healthy adult Korean women who were at least 37 weeks pregnant. Logistic regression analysis was used to identify predictors of GWG. RESULT: Among 139 participants, 42.4 % had inadequate and 20.9 % had excessive gestational weight gain. Quitting smoking for pregnancy (OR = 7.04) was found to be a risk factor for excessive GWG, while perceiving oneself as thin (OR = 0.18), high body image satisfaction (OR = 0.54), and negative attitudes toward weight gain (OR = 0.88) were protective factors for excessive GWG. CONCLUSION: During the first prenatal care visit, smoking history, body image perception, satisfaction, and attitudes toward weight gain, which were identified in this study as predictors of gestational weight gain, should be assessed to identify pregnant women with risk factors. These individuals can be managed in nurse led weight management groups, which may help prevent excessive weight gain during pregnancy and improve pregnancy outcomes.