SummaryObjectivesThis study aimed to investigate weight bias within young children's pro‐social choices between characters who differed in body size.MethodsSeventy‐six children aged 4–6 years read stories asking them to choose who they would first help, share with, comfort, and steal from, between a healthy weight and child with overweight. They also selected the one character they would most like to play with. Children's reasoning for these choices was recorded and analysed.ResultsThe character with overweight was helped first in only a third of the choices made. Children chose the characters with overweight more often as the target for anti‐social action. In friendship selections, children overwhelmingly rejected the characters with overweight. However, weight bias was not prominent in the reasons children gave for the choices. Most children were not negative about body shape, weight or appearance. Similarly, in friendship choices, these were mostly expressed positively to the character chosen. Only a small minority of children were explicitly negative about the character with overweight.ConclusionsA better understanding of weight bias acquisition and variation between children will benefit those working in health care and educational settings. Future research should link with developmental theory, such as on social categorization and theory of mind.