WASHINGTON — President Biden will undergo his first physical as president on Friday, becoming the oldest commander in chief to receive a full medical evaluation while in office and briefly transferring power to Vice President Kamala Harris while he has a colonoscopy.

“As was the case when President George W. Bush had the same procedure in 2002 and 2007, and following the process set out in the Constitution, President Biden will transfer power to the vice president for the brief period of time when he is under anesthesia,” Jen Psaki, the White House press secretary said. “The vice president will work from her office in the West Wing during this time.”

Mr. Biden, who is 78, used Section 3 of the 25th Amendment to temporarily transfer power, the administration said. Under that provision, the president is required to notify the president pro tempore of the Senate, Senator Patrick Leahy, Democrat of Vermont, and Nancy Pelosi, the Speaker of the House, that he is temporarily unable to carry out his presidential duties.

The decision to offer transparency was a marked departure from the information offered by Mr. Biden’s predecessor, Donald J. Trump, who made an unexpected and unexplained visit to Walter Reed National Military Medical Center in November 2019. During that visit, his aides have said, Mr. Trump received a colonoscopy.

Ms. Psaki said the White House would disclose when Mr. Biden underwent anesthesia and when he came out. Mr. Biden’s physical and colonoscopy are at Walter Reed National Military Medical Center.