A knob assembly for a gas valve of a cooking appliance and a method of assembling said knob assembly is provided. The knob assembly can include a knob configured to engage a valve stem of the gas valve and a lock assembly including a locking element and a locking plate. The locking element can include at least one cam element that can be engaged by at least one projection carried by the locking plate. The locking plate can be configured to rotate relative to the locking element between a first position in which the at least one projection engages the at least one cam element and a second position in which the at least one projection is disengaged from the at least one cam element, and wherein in the first position the at least one cam element inhibits actuation of the gas valve by the knob.