A blind Chinese legal activist who was suddenly allowed to leave the country arrived in the U.S. on Saturday, ending a nearly monthlong diplomatic tussle that had tested U.S.-China relations.

Chen Guangcheng had been hurriedly taken from a hospital hours earlier and put on a plane for the U.S. after Chinese authorities suddenly told him to pack and prepare to leave. He arrived Saturday evening at Newark Liberty International Airport and departed the plane out of sight of journalists and more than a dozen supporters. He was...