"This morning I met the king and asked for his consent to dissolve the parliament," Najib said in a televised speech. "This dissolution will pave the way for the 13th general election," he said.
The poll announcement has been awaited for months now. The Election Commission is expected to set a polling date and determine when formal campaigning can begin.
The elections have to be held before June 2.
The Barisan Nasional coalition that has ruled Malaysia since independence in 1957 is expected to face a stiff challenge in the polls from the opposition three-party Pakatan Rakyat (People's Pact), led by the charismatic Anwar Ibrahim, a former deputy premier.
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The Barisan's current mandate ends on April 30. There are 222 seats in Parliament for mandate and control of 12 of Malaysia's 13 states.
The 13-member coalition mainly comprises of the United Movement of National Malays (UMNO) led by Najib, the Malaysian Chinese Association (MCA) comprising ethnic Chinese and the Malaysian Indian Congress (MIC) which comprises ethnic Indians.
Najib urged more than 13 million eligible voters to support the Barisan party. He has launched a series of reforms aimed at boosting the economy and granting civil liberties.
"Do not gamble with the fate of our children and grandchildren," Najib said, adding that he planned to travel to "all corners of the country" in the weeks ahead to speak to voters and win their confidence.
The 13th general election will be the first for Najib as the leader of the Barisan, the Star Online reported.