This study examined linkages between early motherhood (before age 20) and long‐term economic disadvantage, using data from a birth cohort of 509 New Zealand‐born women followed to age 30. Associations between early motherhood and economic outcomes were examined using linear and logistic regression models and were adjusted for a range of prepregnancy factors. The findings suggested that early motherhood was associated with several indicators of economic disadvantage at age 30, including working fewer hours, welfare dependence, lower personal incomes, and exposure to economic hardship. These associations remained statistically significant even after extensive adjustment for confounding factors. These findings suggest that having a child before age 20 leads to long‐term economic disadvantage that persists for at least a decade.