Patriotic songs rang out from the west front of the Capitol. National leaders past and present - including former Presidents Bill Clinton and Jimmy Carter - were on hand to witness the traditional pomp of Obama's second inauguration.
Grammy Award-winning R&B artist Beyonce sang a rousing rendition of the national anthem, in a star-studded line-up that also included Kelly Clarkson and James Taylor.
Yet the occasion was muted compared with four years ago. The crowd was about half of the record 1.8 million who attended in 2009. Obama's signature hope-and-change theme of that event has been overtaken by the political battles with Republicans in Congress over the last four years.
The partisanship was put on hold at least temporarily today as Republican lawmakers offered the president good wishes and the prospect of collaboration in the days to come.
House Speaker John Boehner of Ohio - who has had a frequently rocky relationship with Obama over the last two years - sat next to first lady Michelle Obama and the two clinked glasses at the start of a congressional luncheon after the swearing-in ceremony.
House Majority Leader Eric Cantor of Virginia used Twitter to congratulate Obama an instant after he took the oath, and Senate Republican leader Mitch McConnell of Kentucky said Obama's second term "represents a fresh start" on such issues as "unsustainable federal spending and debt."
"Republicans are eager to work with the president on achieving this common goal," McConnell said in an emailed statement.
The president has presided over an economy that is still recovering from the worst recession in a generation. While the world's largest economy grew at a 3.1 percent rate in the third quarter, this year will bring growth of just 2 percent, according to the median estimate of economists surveyed by Bloomberg.
Over the next two months, his administration will engage in a fiscal debate with Republican lawmakers who hold the majority in the House over raising the government's $16.4 trillion borrowing limit, steps to shrink the deficit and funding federal operations.
Obama made only brief mention of issues of war and peace in his speech, praising the contributions of the U.S. military and saying that strong national security doesn't require "perpetual war."
"We will show the courage to try and resolve our differences with other nations peacefully - not because we are naive about the dangers we face, but because engagement can more durably lift suspicion and fear," Obama said.
As a reminder of the risks for the United States abroad, the State Department said Monday that three Americans were among the hostages killed at an gas complex stormed by Algerian forces after it had been seized by terrorists.
Obama disputed the notion that the country is in decline, asserting that the U.S. still plays the central role on the global stage.
"America will remain the anchor of strong alliances in every corner of the globe, and we will renew those institutions that extend our capacity to manage crisis abroad, for no one has a greater stake in a peaceful world than its most powerful nation," he said.
The day wasn't all pomp, circumstance and bipartisanship. Before striding out to the platform outside the Capitol to take his oath, Obama signed the nominations of his picks for secretaries of Defense, State, Treasury and the Central Intelligence Agency, at least three of which are likely to engender tough confirmation fights.