But in one of the tightest races in German history, they punished her pro-business partner, the Free Democrats, kicking them out of parliament for the first time since 1949, according to the exit polls on public television.
The upstart anti-euro party AfD appeared to fall just short of the five-percent hurdle to representation amid anger over German contributions to bailout packages for stricken eurozone partners.
Under Germany’s complex electoral maths, the result means the most likely scenario will be a left-right “grand coalition” between Merkel’s Christian Democrats and their traditional opponents, the centre-left Social Democrats (SPD), which scored around 26 percent.
Merkel’s conservative Christian Democrats scored about 42 percent, marking a personal triumph for the 59-year-old chancellor.
She led a fractious “grand coalition” during her first term in 2005-2009, with the SPD’s chancellor candidate this time around, Peer Steinbrueck, as her finance minister.
Analysts say the coalition negotiations could drag on for weeks, with the SPD insisting on a national minimum wage and possibly naming the finance minister as the price for getting back in government with Merkel.
A physicist by training Merkel is only the third person to win a third term in Germany after the immediate post-war leader, Konrad Adenauer, and Helmut Kohl, the father of German re-unification.
If she serves at least until 2017, she will become Europe’s longest serving female leader besting Margaret Thatcher who was Britain’s prime minister for 11 years.
While Merkel became Germany’s most popular post-war chancellor, the eurozone crisis laid waste to the careers of leaders in hard-hit countries such as Ireland, Portugal, Italy, Greece, Spain and France.
More generosity, patience for eurozone?
In contrast to Merkel’s austerity-driven response to the eurozone crisis, the SPD has called for a bit more generosity and patience with stricken nations as they pay back their debts.
But analysts note that the SPD has largely backed Merkel’s course in parliamentary votes during four years of crisis and predict little change in Merkel’s strategy of demanding biting reforms in exchange for bailout.
The near success of the AfD, which advocates ditching the single currency and an “orderly dissolution” of the 17-member eurozone, sent a jolt through German politics, where a eurosceptic party has never gained a foothold.
In a last-minute appeal for votes at a Berlin rally Saturday, Merkel had urged voters not to succumb to the AfD’s siren call.
“The stabilisation of the euro is not just a good thing for Europe but it is also in Germany’s fundamental interest,” she said.
Nearly 62 million people were called to the polls after a campaign many voters complained was largely superficial and personality-based.
Economic growth is steady, unemployment at below seven percent – its lowest level in two decades – and the political culture is dominated by a long post-war tradition of consensus rather than red-blooded jousting.
That left few issues to separate the main candidates.
“I think we have a good standard of living in Europe, and for me, this must remain stable. So, to me, voting for the extremes, on the left or the right, isn’t an answer,” Sister Elisabeth Bauer, a nun, told AFP as she cast her vote in Berlin.
The ecologist Greens party, the SPD’s preferred coalition partner, scored around a disappointing eight percent in Sunday’s poll.
And the far-left Linke, which has roots in former East Germany’s ruling communist party, also tallied about eight percent but the SPD has repeatedly ruled out forming a coalition with it at the national level.
The brash, gaffe-prone Steinbrueck stumbled again in the home-stretch of the campaign with a front-page magazine photo of him making a surly middle-finger reply to a question on his limping candidacy.
He had zeroed in on a growing low-wage sector, but it was not enough to dislodge Merkel from the top job.