Over the past decades, growing attention has been paid to how the home and school environment contributes to early mathematical development. Nevertheless, many studies focused on the nature and frequency of the learning activities. The potential influences of parent-child and teacher-child relationships are still underexplored. In view that parents and teachers play vital roles in early language development, and language and mathematical skills are interrelated, we investigated: (1) whether different aspects of parent-child and teacher-child relationships were related to very young children’s mathematical abilities; and (2) whether these relations, if any, were mediated by children’s receptive vocabulary. To achieve our study aims, 124 children were recruited from pre-nursery classes in Hong Kong and were administered vocabulary and mathematical tests. Their parents and class teachers also completed a questionnaire relating to their relationships with the children. Results of path analysis showed that after controlling for children’s age, parent-child closeness, parent-child conflict and teacher-child closeness were associated with children’s mathematical abilities through their receptive vocabulary. There were also direct links from parent-child closeness and teacher-child closeness to children’s mathematical abilities. Teacher-child conflict was neither correlated with children’s receptive vocabulary nor mathematical abilities. Our findings suggest that it is important to provide support to parents and teachers on how to build up close and affectionate relationships with very young children. In particular, they should be coached on how to have quality verbal interactions with children, as it may benefit not only children’s early language development, but also their early mathematical development. Copyright © 2021 HKERA-APERA International Conference.