Thomas' pick-off set up a 1-yard scoring run by Andre Brown, allowing the mistake-prone Giants (3-6) to come away with the victory.
Brown, playing in his first game of the season following a broken leg, finished with 115 rushing yards on 30 carries for New York, which won a third straight.
Eli Manning made good on only 12-of-22 passes for 140 yards with a touchdown and an interception that was returned for a touchdown, but was helped out when the Giants blocked an Oakland punt and ran it in for a score.
Terrelle Pryor completed just 11-of-26 passes for 122 yards, lost a fumble and yielded the key interception for the Raiders (3-6), who dropped their eighth straight road game.
Celebrity Families of 2014 [PHOTOS]