Truro and St Austell was a county constituency in Cornwall represented in the House of Commons of the UK Parliament from its 1997 creation to its 2010 abolition by Matthew Taylor of the Liberal Democrats, who was appointed a life peer in the House of Lords following his service as a Member of Parliament (MP).

In 1997, in spite of the fact that no boundary changes were made to Truro on that occasion, the Boundary Commission nonetheless saw fit to change its name to Truro and St Austell, reflecting the fact that St Austell has a larger population than Truro.

He was succeeded in a by-election the following year by Matthew Taylor, who held the seat comfortably until his retirement, at the constituency's abolition, in 2010.

The constituency was centred on the former district of Carrick (which contains the city of Truro) and the former borough of Restormel (which contains the town of St Austell).

Following a review of parliamentary representation in Cornwall, the Boundary Commission for England created an extra seat for the county which meant consequential changes for the existing seats.