With his wife, Mary Jane Dwyer, Marchant was the
benefactor of many charitable causes, including providing land in
Ann St for the
New Jerusalem Church and in
Chermside, where he donated his horse paddock to the Kedron Shire Council as a park.
Marchant Park is named after him. A ward of the
Brisbane City Council centred on Chermside is also named Marchant Ward. He was a major benefactor in the establishment of the
Canberra Temperance Hotel in Brisbane, which opened in 1929. In 1932, the Queensland Society for Crippled Children was established to care for children with severe physical disabilities arising from the polio epidemic of 1932. In September 1932, Marchant donated his home
Montrose and its 5 acres of gardens at
Taringa to the society to establish an institution for the care and treatment of the children. When the number of children needing care became too many to be accommodated in Montrose, Marchant purchased a property at Consort Street,
Corinda as a new larger facility which continued to be called Montrose (which is still in use for the care of disabled children in 2015). ==Later life==