Fernandez had 53 percent of the votes after 24 percent of polling stations had been tallied nationwide, while her nearest challenger got just 17 percent. Interior Minister Florencio Randazzo predicted the president's vote share would rise, saying very few of the ballots in her party's stronghold of Buenos Aires province, the country's largest, had been counted.
Thousands of the populist leader's supporters crowded into the capital's historic Plaza de Mayo in a jubilant, flag-waving celebration.
Fernandez is Latin America's first woman to be re-elected as president, but the victory was personally bittersweet - the first without her husband and predecessor, Nestor Kirchner, who died of a heart attack last Oct. 27.
Her voice almost broke as she spoke about their shared legacy with a mixture of pride and sorrow after voting in his hometown, the remote Patagonian city of Rio Gallegos. "In this world where they have criticized us so forcefully, all this makes me feel very proud, that we're on the right track," Fernandez said. Kirchner "would be very content."
Fernandez appeared to have won a larger share of votes than any president since Argentina's democracy was restored in 1983, when Raul Alfonsin was elected with 52 percent. Her margin over Gov. Hermes Binner and five other candidates was wider even than the 1973 victory margin of her strongman hero, Juan Domingo Peron.
Her political coalition also hoped to regain enough seats in Congress to form new alliances and regain the control it lost in 2009. At play were 130 seats in the lower house and 24 in the Senate.
Fernandez suffered high negative ratings early in her presidency, but she soared in popularity as a widow by softening her usually combative tone and proving her ability to command loyalty or respect from an unruly political elite.
Most voters polled beforehand said they wanted government stability to keep their financial situations improving in what has been one of Argentina's longest spells of economic growth in history.
Fernandez, 58, chose her youthful, guitar-playing, long-haired economy minister, Amado Boudou, as her running mate. Together, the pair championed Argentina's approach to the global financial crisis: Increase government spending rather than impose austerity measures, and force investors in foreign debt to suffer before ordinary citizens.
Argentina has been closed off from most international lending since declaring its world-record debt default in 2001, but has been able to sustain booming growth ever since.
The country faces tough challenges in 2012: Its commodities exports are vulnerable to a global recession, and economic growth is forecast to slow sharply in the coming year. Declining revenues will make it harder to raise incomes to keep up with inflation. Argentina's central bank is under pressure to spend reserves to maintain the peso's value against the dollar, while also guarding against currency shocks that could threaten Argentina's all-important trade with Brazil.
Boudou could now win attention as a potential successor to Fernandez, but navigating these storms will require much skill and good fortune.
Opposition candidates blamed Fernandez for rising inflation and increasing crime and accused her of politically manipulating economic data and trying to use government power to quell media criticism.
Former President Eduardo Duhalde, who fell from front-running rival to near-last in the polls, said in a dour closing speech that "the country is dancing on the Titanic," failing to prepare Argentina for another global economic crisis.
But economist Mark Weisbrot said Argentina is in far better shape than most countries in the region to face such problems.
U.S. President Barack "Obama could take a lesson from this," said Weisbrot, co-director of the Center for Economic and Policy Research in Washington. "It's an old-fashioned message of democracy: You deliver what you promise and people vote for you. It's kind of forgotten here in the U.S."
The exit polls said Binner, 68, a doctor and governor of Santa Fe province was followed by Ricardo Alfonsin, 59, a lawyer and congressional deputy with the traditional Radical Civic Union party and son of the former president, in third place; Alberto Rodriguez Saa, 52, an attorney and governor of San Luis province whose brother Adolfo was president for a week, in fourth; and Duhalde, who preceded Kirchner as president, in fifth. Leftist former lawmaker Jorge Altamira, 69, and Elisa Carrio 54, a congresswoman who came in second behind Fernandez four years ago, trailed the rest.
When Fernandez is inaugurated Dec. 10, her Front for Victory coalition will become the first political bloc to begin a third consecutive presidential term since 1928, when President Hipolito Yrigoyen of the Radical Civic Union took office, only to be toppled by a military coup two years later, said Leandro Morganfield, a historian at the University of Buenos Aires.
Voting is obligatory in Argentina, and nearly 29 million citizens among the 40 million population were registered.
"I've been a political activist my whole life, but I haven't always been able to vote," Fernandez said, referring to the 1966-1973 and 1976-1983 dictatorships, which tried and failed to eliminate Peronism as an electoral force. "To be able to vote freely in the Argentine republic is an achievement."