A wide-angle LED warning apparatus has a heat sink base, a circuit board, multiple pillars, multiple LED devices and a transparent cover. The circuit board is mounted in the heat sink base. The pillars are formed in the heat sink base and each pillar respectively has an oblique surface, the oblique surfaces facing toward two opposite sides of the heat sink base. The LED devices mounted on a front surface of the circuit board and the oblique surfaces of the pillars. The transparent cover is mounted on the heat sink base. Hence, the LED warning apparatus of the invention can widely emit light due to the LED devices mounted on the oblique surfaces of the pillars to provide enhanced warning effect and security.