He said: "We will start the work on a new government platform.
"I'm confident we'll succeed, as we've had four years of experience with this."
The coalition had needed 85 seats to win an absolute majority and is the first Norwegian government to win re-election in 16 years.
In the last election in 2005, the coalition won 87 seats and the opposition 82.
Opinion polls released before the vote had suggested the government risked losing its hold on the legislature.
"These are good results but we need to keep a cool head"
Raymond Johansen, Labour party secretary
The right-wing populist Progress party, headed by Stoltenberg's main challenger, Siv Jensen, has gained support by pushing for cuts in Norway's notoriously high taxes and tightening immigration rules.
But the opposition was unable to muster a united front.
After she cast her ballot, Jensen blamed Stoltenberg's three-party coalition for bad roads, crowded asylum centres and long waiting lists for non-emergency treatment at public hospitals.
"He has not been able to solve the welfare issues he promised to solve four years ago," the 40-year-old candidate said.
"That is reason enough for a new government."
Oil and gas pumped from North Sea platforms has made Norway, which has a population of 4.8 million, one of the world's richest countries.
Most of the capital is currently reserved for future generations in a sovereign wealth fund valued at more than $400bn.
Jensen's party had wanted to spend more of the proceeds now.
On Sunday, Stoltenberg, 50, dismissed Jensen's platform as "completely wrong for Norway".
He said that Norway, where unemployment stands at three per cent - among the lowest in Europe - had managed to survive the global financial crisis largely unscathed under his government.