He became the 71st Secretary of State in the nation's history. Wednesday became Blinken's first working day at the State Department after his nomination was confirmed by the Senate for the Secretary of State position.
In introductory remarks to State Department personnel, Blinken said the world needs American leadership to address global challenges.
Blinken previously served in the Obama administration as deputy national security adviser from 2013 to 2015 and deputy secretary of state from 2015 to 2017.
He was confirmed by US Senate on Tuesday, in a vote of 78-22, as the diplomat promised to rebuild ties with America's allies and return to talks with Tehran on the Iranian nuclear programme.