Clinicians regularly assess, diagnose and manage illnesses which are directly or indirectly linked to environmental exposures. Yet, various studies have identified gaps in environmental assessment in routine clinical practice. This review assessed clinicians’ environmental health practices, attitudes and beliefs, and competencies and training. Relevant articles were sought using a systematic search strategy using five databases, grey literature and a hand search. Search strategies and protocols were developed using tailored mesh terms and keywords. 43 out of 11,291 articles were eligible for inclusion. Clinicians’ attitudes and beliefs towards environmental health and routine clinical practice were generally positive, with most clinicians believing that environmental hazards affect human health. However, with the exception of tobacco smoke exposure, environmental health assessment was infrequently part of routine clinical practice. Clinicians’ self-competence in environmental assessment was reported to be inadequate. Major challenges were the time required to complete an assessment, inadequate training and concerns about negative patients’ responses. Clinicians have strong positive attitudes and beliefs about the importance of environmental health assessments. However, more concerted and robust strategies will be needed to support clinicians in assuming their assessment and counselling roles related to a wider range of environmental hazards.