A button assembly for pressing a switch in a computer bezel includes a button connected to an arm. A cutout is defined in the computer bezel. The button is inserted in the cutout, and the arm is pivotably mounted on the computer bezel. A pressing portion extends outward from a side of the arm. A slanted pressing plane is formed on the pressing portion. Pressing the button moves the arm so that one end of the slanted pressing plane away from the arm contacts the switch. The switch resists the pressing portion, causing the arm to rotate so that the other end of the slanted pressing plane moves forward, thereby the slanted pressing plane entirely contacts and activates the switch.