She reclaimed the gavel after the most diverse class of lawmakers were sworn in and as Democrats took control of the House after mid-term elections gains.
Her victory came as the US government remained partly shut down in a row over funds for the president's border wall.
Ms Pelosi has said she wants to end the shutdown but will not support the wall.
"I'm particularly proud to be a woman Speaker of the house of this Congress, which marks the 100th year of women having the right to vote," she said.
"And, that we all have the ability and the privilege to serve with over 100 women members of Congress - the largest number in history. "
Ms Pelosi, 78, seized the gavel as the House welcomed more women than ever before in the 116th Congress. SHARE THIS STORY USING ANY OF THE BUTTON BELOW ⬇ PLACE YOUR TEXT ADVERT BELOW ⬇⬇⬇