Elections were to be held in 2012, but President Nursultan Nazarbayev unexpectedly called this week for an early vote.
The measure he signed on Thursday allows for the vote to be held on two months' notice.
The signing was reported by the state news agency Kazinform.
Nazarbayev has led Kazakhstan since the 1991 collapse of the Soviet Union. He has tried to project a democratic image despite detractors accusing him of corruption and undemocratic practices. The parliament has no opposition members.
He called for the early election on the same day that the constitutional court rejected a petition drive for a referendum on keeping him in power for at least another decade.