Sullivan, who was flying Wednesday to the Indianapolis Combine, said he received the paperwork for the designation Wednesday afternoon.
The one-year tender for a cornerback receiving the franchise tag is $9.465 million, currently the average of the top five salaries for cornerbacks in the league. For another team to sign him, they would have to reach agreement on an offer sheet. The Seahawks would have seven days to decide if they wanted to match the offer. If they didn't match the offer, the signing team would have to give the Seahawks two first-round draft choices.
Seahawks president and general manager Tim Ruskell expects Trufant will sign the tender -- or will eventually sign a multiyear deal to stay with the hometown team that drafted the native of Tacoma, Wash., 11th overall in 2003 out of Washington State.
"We are excited that Marcus will remain a Seahawk," Ruskell said. "We will continue to talk with his representative in hopes of securing a long-term deal, which is our goal."
Trufant is coming off his best NFL season, with eight interceptions and his first Pro Bowl appearance. The day after the Seahawks lost in the NFC divisional playoffs at Green Bay Jan. 12, Trufant sounded as if he would like to negotiate with other teams. He said he was "a little curious" to test the free-agent market for the first time.
"I know the organization loves me," Trufant said then. "But that only goes so far. There's always a business side of it. We may want things to be done exactly how we want them to be done, but it can't always be that way.
"I really don't have control over a lot of things ... so I just got to wait around and see what happens."
Trufant and Raiders Nnamdi Asomugha are the two cornerbacks who received franchise tags. Both were tagged on Wednesday.
ESPN.com senior writer John Clayton and the Associated Press contributed to this report