A cable management arm assembly includes first and second arms, a cable base pivotally connected between the arms, a plate fixedly connected to the cable base, a supporting base, first and second supporting members, and a sliding base connected to the plate and slidably connected to the second supporting member. The second supporting member is movably connected to the first supporting member, which is pivotally connected to the supporting base. When the second arm is moved away from the first arm, the cable base is moved away from the supporting base, and the sliding base drives the second supporting member to extend from the first supporting member and the first supporting member to rotate relative to the supporting base (16).