Organisations have flattened and increasingly rely on teamwork. Therefore, colleagues play an increasingly important role in stimulating employee motivation. Adopting Self‐Determination Theory as a guiding framework, the aim of this field experiment was to examine whether team members can be trained in supporting each other's basic psychological needs for autonomy, competence, and relatedness and, hence, increase each other's need satisfaction and autonomous motivation, while decreasing controlled motivation. We delivered training to 146 participants nested in 26 participating teams and assessed basic need satisfaction and autonomous and controlled motivation before and after the intervention. Multilevel regression analyses indicated that employees in the experimental (i.e. intervention) condition had a stronger increase in need satisfaction and autonomous motivation than employees did in the control condition, and that the increase in autonomous motivation was mediated by an increase in need satisfaction. This study provides added value for theory on need satisfaction and demonstrates that a relatively brief intervention among team members may be effective in creating employee need support and increasing autonomous motivation.