In a message posted on Twitter, Thomas emphasized that he wants to "remain a Seahawk for the rest of my career." But Thomas, who is entering the final year of a four-year, $40 million deal, also said he wants to "have certainty in regards to the upcoming years of my career."
"I also believe that based on my production over the last 8 years that I've earned the right to have this taken care of as soon as possible," Thomas wrote. "I want to have certainty in regards to the upcoming years of my career."
Thomas told ESPN at the Pro Bowl in January that he may hold out if he doesn't get a new deal before the season, and he also skipped the Seahawks' voluntary OTAs last month. He would be subject to fines if he were to skip minicamp, though teams can decide to not impose them.
"I hope my teammates understand where I'm coming from," Thomas wrote. "I believe this is the right thing to do."
Seahawks GM John Schneider told reporters before the draft that he was told by Thomas' representatives that Thomas was not planning on holding out.
This year, the maximum fine amounts for missing minicamp are $14,070 for the first day, $28,150 for the second day and $42,215 for the third day, for a total of $84,435. The Seahawks' three-day minicamp starts Tuesday.
Thomas, 29, was the subject of trade speculation earlier this offseason. Seahawks general manager John Schneider never shot down the possibility when asked about it, saying it's his job to listen to all offers. He told Seattle's Sports Radio 950 KJR after the NFL draft in April that the team wasn't trying to trade Thomas.
Thomas and linebacker Bobby Wagner are two of the star defenders who remain with the Seahawks after an offseason of big-name departures. Seattle cut Richard Sherman, traded Michael Bennett, lost Sheldon Richardson in free agency and released Cliff Avril with a failed physical designation. Kam Chancellor's football future is uncertain because of a neck injury. Seattle also lost tight end Jimmy Graham and wide receiver Paul Richardson in free agency.
ESPN's Brady Henderson contributed to this report.