Unity natively imports Blender files. This works under the hood by using the Blender FBX exporter.
To get started, save your .blend file in your project’s Assets folder. When you switch back into Unity, the file is imported automatically and will show up in the Project View.
To see your model in Unity, drag it from the Project View into the Scene View.
If you modify your .blend file, Unity will automatically update whenever you save.
Unity currently imports
All nodes with position, rotation and scale. Pivot points and Names are also imported.
Meshes with vertices, polygons, triangles, UVs, and normals.
Bones
Skinned Meshes
Animations
See Using Blender and Rigify for more details of how to import animated, boned characters into Unity for use with Mecanim.
Requirements
You need to have Blender version 2.60 or later (in some earlier versions of Blender the FBX export was broken).
Textures and diffuse color are not assigned automatically. Manually assign them by dragging the texture onto the mesh in the Scene View in Unity.