Teachers whose basic psychological needs for competence, autonomy and relatedness are satisfied tend to use a motivating teaching style characterised by the provision of autonomy support and structure, whereas teachers whose needs are frustrated tend to use controlling or chaotic styles which are considered de-motivating. Given the importance of an autonomy supportive and motivating teaching style, it is crucial to better understand how it can be fostered and maintained. Since emotion regulation has been shown to affect both teachers’ and students’ well-being, this research tested the hypothesis that it shapes the association between teachers’ need satisfaction or frustration and the adoption of (de)motivating styles. Three hundred teachers filled in questionnaires to assess need satisfaction and frustration, the emotion regulation strategies of reappraisal and suppression, and their teaching styles. The results confirmed the mediating role of reappraisal and the moderation of emotional suppression. Teachers’ need satisfaction was linked with reappraisal, which in turn was related to the autonomy supportive and structuring motivating styles. High emotional suppression related with the adoption of a controlling style independently of need frustration levels. Only low levels of emotional suppression and need frustration lessened the adoption of a controlling style. Theoretical and educational implications are discussed.