Health official Janbaz Afridi says 20-year-old Hilal Khan died on Thursday, a day after he was shot in the head in the northwestern city of Peshawar.
Since Monday, gunmen had launched attacks in across Pakistan on teams vaccinating children against polio. Six women are among the nine anti-polio workers killed in the vaccination campaign jointly conducted with the Pakistani government.
The U.N. has suspended the drive until a government investigation is completed.
Pakistan is one of only three countries where the crippling disease is endemic.
No one has claimed responsibility for the attacks but some Islamic militants accuse health workers of acting as spies for the U.S.