Childhood stunting remains a global public health concern. Little has been documented on the effect of women's decision-making autonomy on child growth in settings where decision-making at the household and community levels is largely dominated by men. To assess the relationship between maternal autonomy and child growth, we analysed data from a cross-sectional study of 422 mothers and their youngest child aged 6–24 months in the Bawku West District of Ghana. The dimensions of women's autonomy measured were decision-making power, freedom of mobility and financial autonomy. We then compared how each dimension was associated with the likelihood of stunting and wasting. The important predictors of child growth and dietary intake as measured by the mean length-for-age Z-score (LAZ) and minimum acceptable (MAD) diet, respectively, were determined using multivariable regression models. The overall composite index of women autonomy (CIWA) showed that 52⋅8 % of women were of high autonomy and half of them had higher autonomy regarding their own and their children's health. After adjusting (multiple regression analysis) for potential confounders, the mean LAZ of children born to women of high autonomy was significantly higher than LAZ of children born to women of low autonomy (β = 0⋅132; 95 % CI 0⋅19, 0⋅95; P = 0⋅004). Similarly, high women's autonomy was a significant independent predictor of meeting MAD (AOR = 1⋅59; CI 1⋅09, 2⋅34). Of all, the dimensions of women's autonomy measured in this study, health care autonomy better predicted child growth and dietary intake. Based on the findings, nutrition policies and interventions that enhance women's decision-making autonomy could have a positive impact on child growth outcomes.