Background: Rapid weight gain (RWG) during infancy increases the risk of excess weight later in life. Nutrition- and feeding practices associated with RWG need to be further examined. The present study aimed to examine nutrition- and feeding practice-related risk factors for RWG during the first year of life. Methods: A population-based longitudinal birth cohort study of 1780 infants, classified as having RWG or non-RWG during 0–3-4, 0–6 and 6–12 months. RWG was defined as a change > 0.67 in weight standard deviation scores. Associations between nutrition- and feeding practice-related factors and RWG were examined with logistic regression models. Results: Of the participating infants, 47% had RWG during 0–3-4 months, 46% during 0–6 months and 8% during 6–12 months. In the fully adjusted models, bottle-feeding at birth and at 3–4 months and nighttime meals containing formula milk were positively associated with RWG during 0–3-4 months (p < 0.05 for all). Breastfeeding at 3–4 months and nighttime meals containing breast milk were negatively associated with RWG during this period (p < 0.001). Bottle-feeding at birth, 3–4 and 6 months and nighttime meals containing formula milk at 3–4 months were positively associated with RWG during 0–6 months (p < 0.01 for all). Breastfeeding at 3–4 and 6 months was negatively associated with RWG (p < 0.01). During 6–12 months, only bottle-feeding at 3–4 months was positively associated with RWG (p < 0.05). Conclusions: RWG was more common during the first 6 months of life and bottle-feeding and formula milk given at night were risk factors for RWG during this period.