Dominant constructions of professionalism in early childhood education can diminish early childhood teachers' and educators' undertaking of advocacy at the systems or political level. In this paper, we propose an ethically grounded construction of professionalism that provides space for professional practice to move beyond the classroom and into the political sphere. Findings from interviews with four early childhood teachers from Australia who undertake systems advocacy as part of their professional practice show that this work is driven by ethical influences that extend beyond the rule-based imperative, in ethical codes, that teachers should undertake systems advocacy. Findings highlight the value of considering systems advocacy as practice that emerges from an interplay of three theoretical foundations of ethics: deontology, utilitarianism and virtue ethics. Implications for teacher professionalism and the building of a teacher disposition that incorporates systems advocacy are considered.