Jefferson grabbed nine rebounds and Walker flirted with a triple-double with 10 assists and nine rebounds as Charlotte notched a fourth win in five games.
Walker's two free throws with 1.6 seconds left iced the victory after Khris Middleton had missed a contested mid-range jumper for the Bucks.
Brandon Knight put in 26 points and distributed 14 assists for Milwaukee.
Middleton finished with 19 points and six rebounds.
Notable deaths of 2014 [PHOTOS]
LeBron James reveals his new Nike shoes