The Oct. 14 election will be Canada's third ballot in four years.
The Conservatives unseated the Liberal Party in 2006 after nearly 13 years in power, but as a minority government the Conservatives have been forced to rely on opposition lawmakers to pass legislation and adopt budgets.
With Harper signaling in recent weeks that he was leaning toward calling early elections, analysts said the Conservatives had a better shot of winning now than if they waited until being forced by the opposition into a vote later, when the Canadian economy might be worse off.
On Sunday, Harper visited Governor General Michaelle Jean and asked her to dissolve Parliament. The governor general is the representative of Britain's Queen Elizabeth II, who is Canada's head of state, but the position is purely ceremonial and obeys the wishes of the prime minister.
"Between now and Oct. 14, Canadians will choose a government to look out for their interests at a time of global economic trouble," Harper said after the meeting.
"They will choose between direction or uncertainty; between common sense or risky experiments; between steadiness or recklessness."
Liberal leader Stephane Dion said the election offers a stark choice between his party and the "most Conservative government in our history."
Harper has said he is running on economic issues and stresses his opposition to an energy tax proposed by the Liberals.
But Robert Bothwell, director of the international relations program at the University of Toronto argued the move was political.
"Harper is going for a majority government. That's really the only issue," he said.
Observers also say Harper wanted a ballot ahead of the U.S. election. Bothwell said if Democrat Barack Obama surges in the next month in the United States, it will help Canada's opposition Liberal party.
"It will be bad for Harper. Canadian politics don't exactly mirror those of the United States but if something happens in the United States it will find an echo in Canada," Bothwell said.
Electoral legislation that Harper helped enact after he came to power in 2006 fixed the date for the next election in October 2009, but a loophole allows the prime minister to ask the governor general to dissolve Parliament.
The Conservatives now fill 127 of the 308 seats in Parliament. The Liberals have 95, Bloc Quebecois 48, the New Democrats 30 and the Greens have one seat. Three seats are held by independents, and four are vacant.
Since becoming prime minister, Harper has extended Canada's military mission in Afghanistan. Canada has lost 96 soldiers and as the death toll approaches 100 the mission could become an issue in the campaign.
Harper also pulled Canada out of the Kyoto Protocol, which commits industrialized nations to reduce greenhouse gas emissions.
Dion, a former environment minister who named his dog Kyoto, wants to increase taxes on greenhouse gas emitters. Dion has moved his party to the crowded left in Canada by staking his leadership on a "Green Shift" tax plan.
The Conservatives have been targeting Dion's plan in television and radio ads, saying it would kill jobs and drive up energy costs even higher than the current high levels. Dion has said he would offset the higher energy prices by cutting income taxes.
Dion hasn't had much success selling the plan to Canadians, many of whom have viewed him as a weak leader ever since he surprisingly won leadership of the party in late 2006.
"I love to be the underdog. I love being underestimated," Dion said.
Many expect Dion to be removed as leader if he loses the election.