A reversible adjustable lumbar support and headrest tilt mechanism is provided for installation on a chair. A side bracket is coupled to each side of the back frame, and a back bracket is pivotably coupled to each side bracket. An actuator is pivotably coupled to the back frame that has an extendable and retractable shaft. In a first orientation, with the actuator shaft extending toward the upper end of the back frame, a headrest back insert is couple-able to and between the back brackets, such that extension and retraction of the actuator shaft rotates the headrest back insert. In a second orientation, with the actuator shaft extending toward the lower end of the back frame, a lumbar push bar is couple-able to and between the back brackets, such that extension and retraction of the actuator shaft rotates the lumbar push bar.