| Dalseong | |
| Native Name Lang: | ko |
| Settlement Type: | County |
| Translit Lang1: | Korean |
| Translit Lang1 Type1: | Hanja |
| Translit Lang1 Info1: | Korean: {{linktext|達|城|郡 |
| Translit Lang1 Info2: | Dalseong-gun |
| Translit Lang1 Info3: | Talsŏng kun |
| Subdivision Type: | Country |
| Subdivision Name: | South Korea |
| Subdivision Type1: | Region |
| Subdivision Name1: | Yeongnam |
| Subdivision Type2: | Provincial level |
| Subdivision Name2: | Daegu |
| Subdivision Type3: | Administrative divisions |
| Area Total Km2: | 426.86 |
| Population As Of: | 2021 |
| Population Total: | 267473 |
| Population Density Km2: | auto |
| Population Blank1 Title: | Dialect |
| Population Blank1: | Gyeongsang |
Dalseong County (Dalseong-gun) is a gun occupying much of south and western Daegu, South Korea. A largely rural district lying along the Nakdong River, it makes up nearly half of Daegu's total area. It is divided in half by a narrow piece of Dalseo-gu that reaches west to the river.
Like the other local government units in South Korea, Dalseong-gun enjoys a moderate degree of local autonomy. The county magistrate and council are elected by the local citizens, although their authority is sharply curtailed. The seat of government is located in Nongong-eup. The current magistrate is Lee Jong-jin.
Dalseong-gun enters historical records in 757, as Daegu-hyeon, a subsidiary of Suchang-gun (modern-day Suseong-gu). Dalseong-gun became part of Daegu Metropolitan City in 1995, as part of a general reform of local governments.
As the near hinterland of Daegu, Dalseong-gun is known as a center of truck farming and tourism. Landmarks of Dalseong-gun include Biseulsan and the Naengcheon resort area beneath Paljoryeong.
The name Dalseong means "Dal Castle," and comes from the earlier name of Daegu, Dalgubeol.
Dalseong-gun is divided into six eup and three myeon. These are in turn divided into 279 ri and 1470 ban.