| Official Name: | Kosamphi Nakhon |
| Native Name: | โกสัมพีนคร |
| Native Name Lang: | th |
| Settlement Type: | District |
| Subdivision Type: | Country |
| Subdivision Name: | Thailand |
| Subdivision Type1: | Province |
| Subdivision Name1: | Kamphaeng Phet |
| Subdivision Type2: | Seat |
| Subdivision Name2: | Kosamphi |
| Subdivision Type3: | Tambon |
| Subdivision Type4: | Muban |
| Established Title: | District established |
| Population Total: | 28347 |
| Population As Of: | 2005 |
| Blank Name Sec1: | Postal code |
| Blank Info Sec1: | 62000 |
| Blank Name Sec2: | Geocode |
| Blank Info Sec2: | 6211 |
| Timezone: | ICT |
| Utc Offset: | +7 |
| Coordinates: | 16.6317°N 99.3483°W |
Kosamphi Nakhon (Thai: โกสัมพีนคร, in Thai pronounced as /kōː.sǎm.pʰīː ná(ʔ).kʰɔ̄ːn/) is a district (amphoe) in the northwestern part of Kamphaeng Phet province, central Thailand.
In Sukhothai Kingdom era, Mueang Kosamphi was a satellite city of the frontier city Mueang Chakangrao (Kamphaeng Phet), at same level as Mueang Nakhon Chum, Trai Trueng, Phan, and Phangkha. Archaeological evidence of the ancient city was found in Ban Khlong Mueang, Tambon Kosamphi.
The minor district was separated from Mueang Kamphaeng Phet district and created on 15 July 1996.[1]
On 15 May 2007, all 81 minor districts were upgraded to full districts.[2] On 24 August the upgrade became official.[3]
Neighboring districts are (from the northeast clockwise) Phran Kratai, Mueang Kamphaeng Phet of Kamphaeng Phet Province and Wang Chao and Mueang Tak of Tak province.
Important water resources are the Ping and Wang Chao River.
The district is divided into three sub-districts (tambons), which are further subdivided into 43 villages (mubans). There are no municipal (thesaban) areas. There are three tambon administrative organizations (TAO).
| No. | Name | Thai name | Villages | Pop. | ||
|---|---|---|---|---|---|---|
| 1. | Kosamphi | โกสัมพี | 25 | 17,627 | ||
| 2. | Phet Chomphu | เพชรชมภู | 9 | 5,437 | ||
| 3. | Lan Dokmai Tok | ลานดอกไม้ตก | 9 | 5,283 |