O'Malley signed a contract to join the Giants' 53-man roster Saturday, Art Stapleton of The Bergen Record reports.
O'Malley spent less than a month on the Bills' practice squad earlier this season and was waived by the Raiders at roster cutdowns in September. Starting tight end Evan Engram (ribs) won't play Sunday against the Redskins, but O'Malley is unlikely to serve as more than a depth option.