Watt was appointed an Officer of the Order of the British Empire on 1 January 1919, in recognition of his war service. He returned to Australia on 6 May with the rest of 1st Training Wing's personnel, aboard the troopship "Kaisar-i-Hind", on which he was the ranking officer. Leaving the AFC soon afterwards, he was elected president of the New South Wales section of the Australian Aero Club. He also served as senior delegate on a committee of veteran military pilots examining applications for appointment to a proposed independent Australian air service. Watt was esteemed as a man who did not forget old comrades, providing former AFC members with financial aid and helping them re-establish themselves in civilian life. He maintained an interest in commercial flying but refused an offer to take up the position of controller of civil aviation in 1920 owing to his business interests, which included partnership in the family shipping firm of Gilchrist, Watt & Sanderson Ltd, and directorships of mining, rubber, and art corporations. He also turned down invitations to stand for parliament, and to join the fledgling Royal Australian Air Force.