Notable among Sellars' architectural achievements was the design of a major department store [later House of Fraser] on Buchanan Street, Glasgow in 1883. He also designed St Enoch's Free Church, Old Dumbarton Road, Glasgow (1871); the Stewart Memorial Fountain in Kelvingrove Park, Glasgow (1872); Andrew’s Halls [subsequently the Mitchell Theatre] in Glasgow (1873); Netherhall House in Largs, Ayrshire for Lord Kelvin (1875); offices of the Employers Liability Assurance Corporation, 75 Nelson Mandela Plac,e Glasgow (1876-77); Greek Orthodox Cathedral of St Luke in the Dowanhill district of Glasgow (1877); Kelvinside Academy, an independent day school in Glasgow (1877); Kelvingrove Parish Church in Derby Street, Glasgow (1878); extension of Ayr Town Hall (1878-81 in Ayr, Ayrshire) ; the New Club at 144-146 West George Street, Glasgow (1879); offices of the Glasgow Herald newspaper on Buchanan Street, Glasgow (1879); Glasgow Victoria Infirmary, a teaching hospital situated at Langside/Battlefield, Glasgow (1882); the entrance archway to Lambhill Cemetery in Glasgow (1882); Gorbals Medical Mission at 46 Gorbals Street, Glasgow (1883-84); various buildings for the International Exhibition in Glasgow (1888); and Anderson College of Medicine at 56 Dumbarton Road, Partick, Glasgow (1888–89; completed after Sellars' death).

The influence of Alexander 'Greek' Thomson (1817-1875) is evident in much of Sellars' work.

Sellars was admitted a member of the Glasgow Institute of Architects in 1872. He died at his house, 9 Montgomerie Crescent in Glasgow on 9 October 1888, the result stepping on a rusty nail at the 1888 Glasgow International Exhibition. The incident led to blood poisoning.

_{Text source: Art History Research net (AHR net)}