swear in

verb

1. To administer an oath to, as an oath of office or of citizenship.

   “The Chief Justice swore him in as President on Inauguration Day.”

   “"Where will you be sworn in?" I asked as we walked to the door. He said that he had decided not to go to the Capitol because his former colleagues there might turn the occasion into some kind of celebration. I said that I planned to be gone by noon; if he liked, he could be sworn in in the White House, as Truman had been.”