An armchair is a chair with arm rests.

Armchair may also refer to:

• Armchair nanotube, a carbon nanotube with chiral symmetry
• Armchair, a sitting sex position
• Armchair (bus company), a bus operator in London
• "Armchair", a song by Avail from their 1996 album 4am Friday

Armchair can also be used as a pejorative modifier to refer to a person who experiences something vicariously rather than first-hand, or to a casual critic who lacks practical experience, in phrases such as armchair revolutionary, armchair general, armchair quarterback, armchair architect and so on.