The Giants also signed wide receiver Johnny Holton. He has 14 receptions for 273 yards and three touchdowns for the Raiders and Steelers since entering the league in 2016.
Halapio, 29, started 15 games for the Giants last season. He has appeared in 27 contests for them over the past three years.
Halapio worked out for the Giants on Tuesday. He surprised them by being in such good shape after suffering a serious injury late last year. His signing is a testament to the hard work he put in this offseason despite being quarantined in Florida.
The former car salesman scrapped his way into the NFL and worked his way into a starting role. Now, he has worked his way back onto the roster after being carted off in Week 17 last season.
To make room for Halapio and Holton, the Giants waived tackle Jackson Dennis and waiver/injured defensive back Jaquarius Landrews.