Unity natively imports Blender files, supporting the following:
See Using Blender and Rigify for more details on how to import animated, boned characters into Unity for animating.
Textures and diffuse color are not assigned automatically. To manually assign them in Unity, drag the Texture onto the Mesh in the Scene View.
Blender does not export the visibility value inside animations in the FBX file.
You need to have Blender installed to import .blend files.
If you don’t have Blender installed, you need to export it to the FBX format, which Unity imports natively. For more information about importing FBX files, see Importing models.
When Unity imports a Blender file, it launches Blender in the background. Unity then communicates with Blender to convert the .blend file into a format Unity can read.
The first time you import a .blend into Unity, Blender has to launch in a command line process, which can take a while, but subsequent imports are very quick.