Yes,it will .i have been using one for about a year. I went round and round with a DJI uninformed phone rep. I asked if it would work ,she said no. I told her I wanted to control my gimbal....again I was told no because my FC40 didn't have a gimbal...I ordered one off Amazon for $99.00 ,if it didn't work I would send it back. Well it worked and controlled my Walkera gimbal perfectly.
That's good to know I got tired of the gimbal controller already on the back of the FC40 controller so I will be looking out to upgrade the controller soon!