Yes, cinnamon is generally allowed in Jain diet because it is a plant-based spice and is not a root, bulb, or tuber.

However, in some strict Jain observances or during vrat / tapas / ayambil-type practices, spices may be restricted or used very sparingly. So the rule can depend on the specific vow or tradition being followed.

In normal Jain food practice, cinnamon is usually acceptable.