Smith caught his own pass on the play.
He stayed in for one more play after a timeout, chirping at Giants safety Xavier McKinney in between plays.
After reaching the sideline following the possession, Smith was testing his leg, running up the sideline, before entering the blue medical tent. Tyler Lockett and DK Metcalf both went into the tent to check on their quarterback.
Drew Lock entered the game with 3:05 left in the half, with Smith exiting up the tunnel.
Smith is 9-of-11 for 67 yards and a touchdown.
His departure came shortly after left guard Damien Lewis was carted off the sideline. Lewis is questionable to return with an ankle injury.
The Seahawks already were without starting right guard Phil Haynes, who earlier in the game was ruled out with a calf injury.
Evan Brown slid to left guard, and Olu Oluwatimi entered at center.