| Lanleff | |
| Native Name: | Lanleñv |
| Commune Status: | Commune |
| Coordinates: | 48.6936°N -3.0433°W |
| Insee: | 22108 |
| Postal Code: | 22290 |
| Arrondissement: | Guingamp |
| Canton: | Paimpol |
| Mayor: | Josette Connan[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | Guingamp-Paimpol Agglomération |
| Elevation Min M: | 17 |
| Elevation Max M: | 86 |
| Area Km2: | 2.16 |
Lanleff (pronounced as /fr/;) is a commune in the Côtes-d'Armor department of Brittany in northwestern France.
Lanleff has an oceanic climate (Köppen climate classification Cfb). The average annual temperature in Lanleff is . The average annual rainfall is with December as the wettest month. The temperatures are highest on average in July, at around, and lowest in January, at around . The highest temperature ever recorded in Lanleff was on 19 July 2016; the coldest temperature ever recorded was on 11 December 1991.
Inhabitants of Lanleff are called lanleffois in French.