Jim Brown is going to bat for Hue Jackson ... telling TMZ Sports the bitterness toward Cleveland's ex-head coach needs to end.
Of course, Hue took only a few days to join up with the Browns' rivals -- the Bengals -- after he got canned in Cleveland ... and dudes like Baker Mayfield were REALLY upset about it.
But Jim tells us the QB and others shouldn't be ... saying Hue made "a good move."
"No bitterness with him. He's got a job right away.