Understanding growth patterns and their determinants among children of Indian-born mothers in Australia is limited. This study assessed the longitudinal growth trajectories of children born to Indian immigrant mothers in Australia and their associations with child and maternal characteristics as well as infant feeding practices. Data from an online survey of Indian immigrant mothers living in Australia and their full-term children aged 1.5–5 years (n = 110) were analysed. Mothers reported child sex, maternal factors, infant feeding practices, and transcribed repeated measurements of child length/height and weight from ages 0 to 42 months from the child health record book. Group‐based trajectory modelling identified subgroups of children following distinctive trajectories of body mass index (BMI) z-score from ages 0 to 42 months. Two distinct healthy BMI z-score trajectories of relatively low and high BMI z-scores were identified. About half (52.2%) of the children showed a slow-rising trajectory, with BMI z-scores ranging from -1.0 to -0.6 units from birth to age 42 months, and 47.8% exhibited a similar trajectory with higher BMI z-scores ranging from 0.2 to 1.6 units. Multivariable logistic regression was used to assess factors associated with identified BMI z-score trajectories. Maternal factors, child’s sex and other infant feeding practices (ever introduced to formula, introduction to solids after 6 months) were not associated with the identified BMI z-score trajectory groups. Longer breastfeeding duration (months) (OR: 1.08; 95% CI:1.01,1.16, p=0.02) was associated with 8% higher odds of following the ‘healthy high BMIz’ than the ‘healthy low BMIz’ trajectory group, highlighting the importance of breastfeeding promotion. Two healthy growth trajectories of low and high BMI z-scores were observed with breastfeeding duration identified as a potential determinant. These findings highlight the potential role of breastfeeding in supporting healthy early childhood growth among children born to Indian immigrant mothers.