Valid patient consent is a legal and ethical principle that is fundamental to healthcare provision. Oral health practitioners (OHPs) must understand the principles that need to be addressed to ensure that the consent given by a patient is valid. Failure to obtain consent may result in a negligence claim or a complaint of professional misconduct against the OHP. Orthodontic treatment is mostly elective but is not without risk to the patient. Obtaining and maintaining valid consent for orthodontic treatment presents additional challenges in comparison with other dental procedures as the treatment lasts over a longer time and is most commonly performed in adolescents. In addition, prospective patients need to be informed regarding 'lifelong' management in the retention phase to minimise the risk of relapse. The present paper outlines the principles of valid consent with particular regard to orthodontic treatment in the adolescent patient. OHPs must ensure that they are satisfied that the competent patient has the capacity to voluntarily consent. Clinicians must also recognise that valid consent is not a one-off 'tick the box' procedural exercise but an ongoing process of effective information sharing in light of changing laws and an ever-changing scientific evidence base within a patient-centred model of healthcare.