Donald Trump pledged to put “America first” and vowed to “rebuild our country and restore its promise for all of our people” as he was sworn in as the 45th president of the United States.
The new president took the oath of office on the steps of the Capitol building as his family and outgoing president Barack Obama watched.
A Bible between them, Mr Trump was sworn in by Chief Justice John Roberts just before noon local time (5pm), before the two men shook hands.
Delivering his inaugural address, President Trump said: “Every decision on trade, on taxes, on immigration, on foreign affairs will be made to benefit American workers and American families.
“We must protect our borders from the ravages of other countries making our products, stealing our companies and destroying our jobs.”
He added: “America will start winning again, winning like never before.”
Promising to “make America great again”, President Trump said: “From this day forward it is going to be only America first, America first.”