Guissény (French pronunciation: [ɡiseni]; Breton: Gwiseni) is a commune in the Finistère department of Brittany in north-western France.

Guissény is a coastal town on the English Channel that is part of the "pays Pagan". It is limited to the northeast by a marine gulf, the gulf (or cove) of Tressény, into which flows a small coastal river, the Quillimadec, which separates it from Kerlouan. To the west, it is limited by the Porz Olier (its eastern tip containing Dibennou and its western Beg ar Skeïz), a small residual marine gulf that was once much larger. Most of the gulf has been transformed into a polder (La Palud de Curnic, where salt marshes once existed) or pond (Étang du Curnic) due to the construction of a dyke that separates Guissény from Plouguerneau. Guissény extends westward to include a good part of the beach of Vougo - the other part being in Plouguerneau - where the coastal dunes reach an altitude of up to 13 meters at a place called "la Sècherie".

To the west of Curnic, the coastal platform is several hundred meters wide and includes a number of emerged rocky islets: Karreg Hir (the Karreg Hir causeway extends northwest to the rocks of Lizenn Du and includes numerous islets emerging at low tide), Golhédoc, Énez Du, Tilloc, and Énez Croaz-Hent (the latter now being linked to the mainland by a dyke).

The inhabitants of Guissény are called Guisséniens in French.

Historical population

Year	Pop.	±% p.a.
1968	2,104	—
1975	1,948	−1.09%
1982	1,887	−0.45%
1990	1,850	−0.25%
1999	1,783	−0.41%
2007	1,823	+0.28%
2012	2,033	+2.20%
2017	2,009	−0.24%
Source: INSEE

In 2009, 21.55% of primary-school children attended bilingual schools, where Breton language is taught alongside French.

• Communes of the Finistère department
• List of the works of Bastien and Henry Prigent

• Mayors of Finistère Association (in French);

• Official website (in French)