| Official Name: | Llanos Costa |
| Settlement Type: | Barrio |
| Seal Size: | 90 |
| Pushpin Map: | Caribbean |
| Pushpin Map Caption: | Location of Puerto Rico |
| Coordinates: | 17.9793°N -67.1411°W |
| Coordinates Footnotes: | [1] |
| Subdivision Type: | Commonwealth |
| Subdivision Name: |  Puerto Rico |
| Subdivision Type1: | Municipality |
| Subdivision Name1: | Cabo Rojo |
| Unit Pref: | Imperial |
| Area Total Sq Mi: | 23.49 |
| Area Land Sq Mi: | 19.52 |
| Area Water Sq Mi: | 3.97 |
| Population As Of: | 2010 |
| Population Note: | Source: 2010 Census |
| Population Total: | 3571 |
| Population Density Sq Mi: | 182.9 |
| Timezone: | AST |
| Utc Offset: | -4 |
| Elevation Ft: | 223 |
| Postal Code Type: | ZIP code |
| Postal Code: | 00623 |
Llanos Costa is a barrio in the municipality of Cabo Rojo, Puerto Rico. Its population in 2010 was 3,571.[2] [3] [4]
Llanos Costa was in Spain's gazetteers[5] until Puerto Rico was ceded by Spain in the aftermath of the Spanish–American War under the terms of the Treaty of Paris of 1898 and became an unincorporated territory of the United States. In 1899, the United States Department of War conducted a census of Puerto Rico finding that the population of Llanos Costa barrio was 867.[6]