Looking ahead to his second-term agenda, the president said the nation must "respond to the threat of climate change" and tackle the comprehensive immigration reform that has eluded Washington for years.
"Our journey is not complete until we find a better way to welcome the striving, hopeful immigrants who still see America as a land of opportunity," he said.
Moments earlier, Obama placed his hand on two Bibles — one used by the Rev. Martin Luther King Jr. and the other used by Abraham Lincoln — and recited the brief oath of office. Michelle Obama held the Bibles, one on top of the other, as daughters Malia and Sasha looked on.
Vice President Joe Biden was also sworn in for his second term as the nation's second in command.
Monday's oats were purely ceremonial. The Constitution stipulates that presidents begin their new term at noon on Jan. 20, and in keeping with that requirement, Obama was sworn in Sunday in a small ceremony at the White House.