Winfield, who will turn 36 this season, was surprised when the Minnesota Vikings released him last month, making him an unrestricted free agent.
Winfield visited the Seahawks on Tuesday after meeting with the Washington Redskins last week.
If the Seahawks sign Winfield, it would further strengthen one of the league's premier secondaries.
Winfield could be the slot corner with starters Richard Sherman and Brandon Browner playing outside. Sherman and Browner combined for 11 interceptions last season, but no other Seattle cornerback contributed any to the team total.