The Selwyn District is a predominantly rural area in central Canterbury, on the east coast of the South Island. It has a land area of 6,420.38 km², mainly consisting of hill and mountain ranges and narrow river valleys. The total population of Selwyn District was 44,595 in the 2013 Census. 2013 Census information confirmed that Selwyn District is the fastest growing area of New Zealand. Selwyn’s population grew from 33,642 to 44,595 between 2006 and 2013, a 33% increase. The largest towns are Darfield, Leeston, Lincoln, Prebbleton, Templeton and Rolleston which is also the home of the Council's main office.

Much of the district's economy is based around farming. Most of this is pastoral: beef cattle and sheep in drier areas, and dairy and deer farming in wetter areas. Some horsebreeding is also done. There is also a substantial amount of cropping; wheat and barley are grown on the plains, along with smaller amounts of grapes and other fruit, vegetables, mushrooms and flowers. The town of Lincoln is home to a University and a number of Crown Research Institutes and other organisations concerned with scientific research. Rolleston is also home to IZONE - New Zealand's largest business park.The Selwyn District Council owns 11% shareholding in Orion, the local electricity distribution company. Selwyn District experienced the strongest economic growth of any district in New Zealand in 2012, with employment growing by 9.5%, compared to the national average of 1%. 1,200 new jobs were created in the district in 2012.

The district is governed by an elected mayor and a council of 10 members. The current mayor is Kelvin Coe who was elected in October 2013.