South Glamorganshire was a parliamentary constituency in Glamorganshire, Wales. It returned one Member of Parliament (MP) to the House of Commons of the Parliament of the United Kingdom, elected by the first past the post system.

The constituency was created by the Redistribution of Seats Act 1885 for the 1885 general election. Of all the Glamorgan seats created by the 1885 redistribution, South Glamorgan was the only one where the Liberal Party could not be assured of victory. The Bute and Dunraven families exercised a powerful influence. The mining areas in the north of the constituency, including the lower reaches of the Rhondda, and the cosmopolitan town of Barry were strongly Liberal but these were juxtaposed against the conservatism of the Vale of Glamorgan and the genteel settlements of Penarth and Llandaff.^[1]

The constituency was abolished for the 1918 general election.

Created in the redistribution of seats in 1885 from the old Glamorganshire constituency which had been in existence since 1541, the seat covered a wide area that included Bridgend, Porthcawl, Coity, Ewenny, Ogmore, Llanharry, Llanharan, Llantwit Major, Dinas Powis, Pendoylan, Bonvilston, Barry, Penarth, Tonyrefail, Pontyclun and Beddau, and areas which are now part of Cardiff (including St Fagans, Radyr, Whitchurch, Llanishen and Lisvane). Cowbridge and Llantrisant were excluded from South Glamorganshire, being contributory boroughs of Cardiff District of Boroughs constituency.

The constituency was scrapped in the next redistribution of seats that took place in 1918.

• A map of Glamorganshire in 1885, showing its new divisions.
• Boundary Commission Map Report from 1885 showing detailed original maps used
• The National Library for Wales: A Dictionary of Welsh Biography (Windham Henry Wyndham-Quin, 5th Earl Dunraven and Mount-Earl)
• The National Library for Wales: A Dictionary of Welsh Biography (William Brace)