From 1980-98 he was judge of the European Court of Human Rights at Strasbourg, the only non-European judge in that court. He was a member of the Permanent Court of Arbitration, at The Hague in 1984, an Honourary Professor in the Law Department of Peking University (1986-98), and was President at the World Academy of Arts and Science (1983-87). Macdonald returned to the U of T in 1990 as senior scholar in residence.
Macdonald became an Officer of the Order of Canada in 1984, and was promoted to Companion in 2000. In 1999, he was awarded the Ramon John Hnatyshyn Award for Law by the Canadian Bar Association to recognize his "outstanding contribution to the law or legal scholarship in Canada." He was awarded honorary degrees from McGill University, Dalhousie University, and Carleton University.
The Canadian Council on International Law established the Ronald St. John Macdonald award to recognize his contributions and accomplishments.