Trewoon, pronounced true-un, (Cornish: Trewoen) is a village in south Cornwall, United Kingdom. It is situated on the western outskirts of St Austell on the A3058road, about one mile from the town centre.

Trewoon is mentioned in the Domesday Book (Tregoin: Hamelin from the court of Mortain) and was part of the St Mewan Parish and had its own manor known as Hembal Manor.

The Manor house has been altered over the years and is now an 8 bedroomed home with the original Coach House converted into 3 cottages.

It is a linear settlement, with various housing estates, and a village hall. It contains local businesses including: a garage, a post office, a busy local store, hairdressers, "The White Pyramid" pub, a social club and a Methodist church (Trinity Methodist Church). The A3058 is a very popular commuter and tourist road that links St Austell and Newquay and is thought to be one of the most dangerous roads in Cornwall with a lot of serious and some fatal accidents although only a few happen in the village itself.

Trewoon is also where the Trewoon Pantomime Group was founded and performed in the local village hall until recently moving to the St Austell Church Hall where they still perform once a year. A second pantomime group has also been formed recently – which does use the village hall for pantomimes.

It has a history of carnivals on an annual basis and happens once a year in the month of August along with fun events, concerts and games that happen all week at various sites in the village.

Trewoon also has a major part to play in the china clay industry in Cornwall being the home to the Blackpool Clay Pits and Dryers. Imerys is the largest employer in the area. Blackpool Pit closed on the 30th November 2007 and Imerys confirmed that some of its operations would be moving to Brazil. There has since been further cut backs estimated to cost the local economy around £12M a year.