A low-profile light-emitting diode (LED) lamp includes a base, a cover, a heat dissipation plate, an LED module, a circuit board, and a light guide hood. The base and the cover respectively form a base opening and a cover opening. The base and the cover include a recess-projection mating structure therebetween to form an outer water sealing wall and an inner water sealing wall that surround the base opening and the cover opening. The light guide hood, the circuit board, and the LED module are arranged inside the inner water sealing wall. The base and the cover are fixed together through recess-projection mating formed between posts and holes to also realize water resistance. The heat generated by the LED module is dissipated by the heat dissipation plate, which is set on an outer surface of the base and is provided with a plurality of convection chambers that induce heat convection.