Plaffeien (French: Planfayon; Arpitan: Pllanfayon [plɑ̃faˈjɔ̃] ) is a municipality in the district of Sense in the Canton of Fribourg in Switzerland . It is one of the municipalities with a large majority of German speakers in the mostly French speaking Canton of Fribourg.

Plaffeien is first mentioned in 1148 as Planfeiun. In 1339 it was mentioned as Blanfeyen.

The name Plaffeien probably comes from the Latin "planum-fageum" meaning beech forest and therefore may date to the Roman era. The spelling of the name changed over time.