A cable management arm includes a first arm, a second arm, a frame, an extension board, a support seat, a first support member, a second support member and a slide. The frame is pivotably connected between the first and second arms. The extension board is connected to the bottom of the frame. The first support member is pivotably connected to the support seat. The second support member is slidably connected to the first support member. The slide is pivotably connected to the extension board and the frame and slidably connected to the second support member. When the second arm is pulled relative to the first arm, the frame is moved from the support seat by sliding the slide along the second support member. The slide moves the second support member to extend relative to the first support member, so that the first support member swings relative to the support.