| Mietoinen | |
| Official Name: | Finnish: Mietoisten kunta Swedish: Mietois kommun |
| Native Name: | Mietoinen – Mietois |
| Settlement Type: | Former municipality |
| Mapsize: | 150px |
| Pushpin Mapsize: | 150px |
| Subdivision Type: | Country |
| Subdivision Name: | Finland |
| Subdivision Type1: | Region |
| Subdivision Name1: | Southwest Finland |
| Subdivision Type2: | Sub-region |
| Subdivision Name2: | Vakka-Suomi |
| Established Title: | Charter |
| Established Date: | 1865 |
| Extinct Title: | Merged with Mynämäki |
| Extinct Date: | 2007 |
| Area Footnotes: | [1] |
| Area Total Km2: | 73.55 |
| Area Land Km2: | 59.50 |
| Area Water Km2: | 14.05 |
| Population As Of: | 2006-12-31 |
| Population Footnotes: | [2] |
| Population Total: | 1697 |
| Population Density Km2: | auto |
| Demographics1 Info1: | % |
| Demographics1 Info2: | % |
| Demographics1 Info3: | % |
| Demographics1 Info4: | % |
| Demographics2 Title1: | 0 to 14 |
| Demographics2 Info1: | % |
| Demographics2 Title2: | 15 to 64 |
| Demographics2 Info2: | % |
| Demographics2 Title3: | 65 or older |
| Demographics2 Info3: | % |
| Blank1 Name: | Climate |
| Blank1 Info: | Dfb |
| Timezone: | EET |
| Utc Offset: | +2 |
| Timezone Dst: | EEST |
| Utc Offset Dst: | +3 |
| Coordinates: | 60.6264°N 21.9292°W |
| Postal Code Type: | Postal code |
| Website: | www.mietoinen.fi |
Mietoinen (in Finnish ˈmie̯toi̯nen/; Swedish: Mietois) is a former municipality of Finland. It was joined to the municipality of Mynämäki in the beginning of the year 2007.
Mietoinen is located in the province of Western Finland and is part of the Southwest Finland region. The municipality had a population of 1,697 (31 December 2006) and it covered a land area of . The population density was .
The municipality was unilingually Finnish.