The South Yorkshire Mayoral Combined Authority (SYMCA) is the combined authority for South Yorkshire in England, with powers over transport (public transport and major trunk roads only), economic development and regeneration. It covers a total area of 3,484 km² (1,345 sq mi) with a population of 1.4 million. The four metropolitan boroughs of South Yorkshire – Sheffield, Rotherham, Doncaster and Barnsley – are full members of the authority, while the Derbyshire Dales, North East Derbyshire, Chesterfield and Bolsover districts of Derbyshire, and the Bassetlaw district of Nottinghamshire, are non-constituent members.

The authority's first mayoral election took place on Thursday 3 May 2018, coinciding with the 2018 United Kingdom local elections.

Until 16 September 2021, the statutory name of the combined authority was the Barnsley, Doncaster, Rotherham and Sheffield Combined Authority (though it was never branded as such). Between April 2014 and May 2018, the combined authority was branded as the Sheffield City Region Combined Authority, and between May 2018 and September 2021 as the Sheffield City Region Mayoral Combined Authority. On 17 September 2021, both its legal name and its brand name changed to the South Yorkshire Mayoral Combined Authority.

The Sheffield City Region was one of eight city regions defined in the 2004 document Moving Forward: The Northern Way, as a collaboration between the three northern regional development agencies.

In September 2006, the local authorities comprising the Sheffield City Region launched the Sheffield City Region Development Programme. This set out how the local authorities believed that by working together as a city region they could increase the economic output of the area by 12.6% by 2016.

It also described governance structures for the city region, including a City Region Forum (consisting of the Leaders of each of the constituent authorities, including the two county councils and the Peak District National Park Authority, along with observers from the two Regional Development Agencies and Government Offices covering the city region). The City Region Forum has since been formally established, and has resolved to set up four thematic Joint Issue Boards to take forward some of the propositions made in the City Region Development Programme. The four Joint Issue Boards cover transport; Residential Offer (Housing Supply and Demand); Destination Management (Tourism and Inward Investment); and Knowledge Economy and Innovation.

The region began its work properly in 2008, with a development forum created. This was to be headed up by Sylvia Yates, the former director of South Yorkshire Objective One European grants programme before the European funding was lost.

The Combined Authority was established by statutory instrument under the Local Democracy, Economic Development and Construction Act 2009 on 1 April 2014. The statutory name of the authority is the Barnsley, Doncaster, Rotherham and Sheffield Combined Authority.