A lamp assembly (100) includes a lamp base (3) having a peripheral wall (31) and a rear wall (32) connecting to the peripheral wall to form a socket (30) with a front opening, with a cable passage (321) recessed forwardly from a back surface of the rear wall and communicated with the socket, a cavity (37) defined in the rear wall and further communicated with the cable passage (321), and a engaging member (371) located in a lower portion of the cavity and proximate to the cable passage; at least a cable (4) inserted into the cable passage, with the engaging member (371) deformed to lock therein so as to prevent the cable sliding out of the cable passage; a lamp bulb (1) partially received in the socket of the base, with a pair of legs (13) thereof extending into the socket and contacting conductors of the cable.