With 91 percent of the vote counted, the Democratic incumbent was comfortably ahead of Republican challenger Mitt Romney 52 percent to 47 percent.
Obama made his final campaign speech of the election campaign Monday night in Des Moines, considered a battleground state in the presidential election -- and one that gave him a boost in his 2008 victory.
"I've come back to Iowa one more time to ask for your vote," Obama said Monday. "Help us finish what we started because this is where our movement of change began."
In a pair of closely watched congressional races, Republican incumbent Steve King was re-elected to a sixth term in the 4th District over Democratic challenger Christie Vilsack, wife of U.S. Agriculture Secretary Tom Vilsack.
The controversial King, whose combative style and unwavering conservative positions have earned him the ire of liberals, led by a margin of 54 percent to 43 percent with 95 percent of the votes counted.
And in a race that pitted two incumbents due to redistricting, Republican Tom Latham bested Democrat Leonard Boswell.
Latham led Boswell 52 percent to 44 percent with 99 percent of precincts reporting.