| Trấn Yên District | |
| Settlement Type: | District |
| Native Name: | Huyện Trấn Yên |
| Subdivision Type: | Country |
| Subdivision Type1: | Region |
| Subdivision Name1: | Northeast |
| Subdivision Type2: | Province |
| Subdivision Name2: | Yên Bái |
| Seat Type: | Capital |
| Seat: | Cổ Phúc |
| Unit Pref: | Imperial |
| Area Total Km2: | 691 |
| Population As Of: | 2003 |
| Population Total: | 96,949 |
| Timezone: | UTC + 7 |
| Utc Offset: | +7 |
Trấn Yên is a rural district of Yên Bái province, in the northeastern region of Vietnam.
As of 2003 the district had a population of 96,949. The district covers an area of 691 km². The district capital lies at Cổ Phúc.
Tran Yen district has 21 commune-level administrative units, including Cổ Phúc town (district capital) and 20 communes: Báo Đáp, Bảo Hưng, Cường Thịnh, Đào Thịnh, Hòa Cuông, Hồng Ca, Hưng Khánh, Hưng Thịnh, Kiên Thành, Lương Thịnh, Minh Quán, Minh Quân, Nga Quán, Quy Mông, Tân Đồng, Vân Hội, Việt Cường, Việt Hồng, Việt Thành, Y Can.