The Giants activated quarterback Davis Webb and wide receiver Marcus Johnson off the practice squad Saturday, ahead of Sunday's game against the Green Bay Packers in London.
New York also signed defensive back Tony Jefferson from the practice squad to the 53-man roster.
Webb's activation comes amid injuries to starter Daniel Jones (ankle) and Tyrod Taylor (concussion).
Taylor is out for Week 5.
Jones, meanwhile, is set to start.
Webb, 27, becomes the Giants' backup against the Packers.
"That's why I wanted to keep playing, too, and not coach," Webb said this week. "I think you do want to play but Daniel's the starting quarterback here and Tyrod's the backup. I'm going to continue to work to get an opportunity."
The Giants signed Webb, who has not attempted a pass in an NFL regular-season game, to a reserve/futures contract Feb. 7 before joining the practice squad Aug. 31.
Webb, whom the Giants selected with a third-round pick in the 2017 NFL Draft, was previously on the Jets (2018) and Buffalo Bills (2019-21).
In Buffalo, Webb played under Giants head coach Brian Daboll, who was the Bills' offensive coordinator from 2018-21.
