Software:
Blender 2.8
To select bones while in Weight Paint mode in Blender 2.8:
- Select the Armature
- Shift select the skinned mesh
- Switch mode to Weight Paint
- Shift-Click bones to select them
* Shift double click to select bones hidden under the mesh
Update:
This has also been verified on Blender 3.6

Thanks, just what I needed!
Glad you found this useful! 🙂
If you select the mesh in the outliner tree, I think you should use Ctrl-Click and not Shift. I tried – with Shift it selects also all objects in between the two you wanted to select. Ctrl-Click selects only the ones you click on. However, when clicking in the scene, use Shift-Click. Blender can be so confusing with these inconsistencies…
It simply doesn’t work for me. It selects all bones at once and none specifically.
Same here sadly. I am not leaving a comment in the hopes of a solution. just letting people in the future know they are not alone. Tried so many things already.. I had like 5 things people told me to chance.. but nothing worked. I select them all. Did you find a solution?
I just checked this again on Blender 3.6 and it works as expected.
Make sure your paint mask or vertex selection is unselected (two little icons to the right of where it says “weight paint mode” in the window), as well as “lock object modes” in the Edit menu (top left).