Electroconvulsive therapy (ECT) is a highly effective treatment option for severe mental illness. Although people with intellectual disability (ID) have similar prevalence rates of mental disorders in comparison to the general population their access to ECT remains challenging. A systematic literature review was carried out on treatment with ECT in patients with ID and a case report on a patient with ID who underwent ECT is presented, to highlight a typical clinical routine. A total of 100 articles with 208 different case reports were retrieved. In summary, the results underline the effectiveness of ECT in people with ID, with side effects comparable to those in the general population. The ECT is effective in the treatment of severe affective and psychotic disorders and particularly in people with catatonia. The use of ECT can improve the patient's mental health and quality of life and is often a life-saving treatment option. The prophylaxis of relapses should be included as early as possible in the planning process. Providing an easy access to ECT treatment for people with ID is corroborated by its effectiveness and is in line with the right to equal treatment in accordance with article 25 of the United Nations Convention on the Rights of Persons with Disabilities.