In recognition of his accomplishments at the OECD, Johnston was awarded the Grand Cordon of the Order of the Rising Sun, the second most prestigious Japanese decoration and the highest one that can be bestowed on a non-Japanese citizen. He received the Grand-Croix de l’Ordre de Léopold II, one of the highest honorific distinctions in Belgium, given by royal decree and generally reserved for heads of state. He was also presented with the Commander’s Cross with the Star of the Order of Merit of the Republic by the President of Hungary and the Order of the White Double Cross, First Class, by the President of the Slovak Republic.