Schofield announced on his Twitter page Friday that he was re-signing with the Seahawks. Jefferson's agent also tweeted about the cornerback joining the Seahawks.
The Seahawks confirmed later Friday that both players had agreed to terms with the team.
Schofield proved important early last season when injuries hit the Seahawks defense. Schofield appeared in 15 regular-season games with two starts. He finished with one sack and appeared in two playoff games. Schofield agreed to a deal with the New York Giants in free agency but the deal was voided.
Jefferson appeared in 25 games combined over the past two seasons with Minnesota. His best season came in 2011 with Arizona when he had 59 tackles and one interception.
Seattle also announced moves on its coaching staff, adding Chris Morgan as an assistant offensive line coach, Chad Morton as an assistant special teams coach and Will Harriger as an offensive assistant. Morgan comes to Seattle from the Washington Redskins, while Morton most recently worked for Green Bay once his playing career ended. Harriger was most recently coaching at Florida.
The Seahawks also announced that Nate Carroll - son of coach Pete Carroll - will now be Seattle's assistant wide receivers coach and John Glenn will be a quality control coach for the defense.