In 1922, McBrien became secretary of the Authorised News Agents' Association of Victoria, a position he held for seven years.
In addition, he was a director of Disher & McBrien Pty Ltd. McBrien held many public posts: chairman of the Edith Cavell Fund Trust, the Homes for Aged and Infirm Society, and the Yarra Bend National Park Trust; honorary treasurer of the Travellers' Aid Society and of the Victorian Anti-Sweating and Industrial Improvement League; executive-member of the Playgrounds and Recreation Association of Victoria; and trustee of the Heidelberg branch of the Returned Sailors', Soldiers' and Airmen's Imperial League of Australia.
McBrien was instrumental in the VFL buying its first head office, Harrison House, in Spring Street, Melbourne, in 1929.
McBrien recruited other key administrators of the VFL, including Eric McCutchan and Jack Hamilton.
On 16 July 1919, McBrien married Madge Margaret Summers at St Luke's Anglican Church, South Melbourne.