Dorsett signed a one-year pact with the Seahawks in March. He was also a free agent last off-season, but opted to return to the Patriots on a one-year pact instead of signing with Seattle.
"I could have came last year, and I chose to stay in New England," Dorsett told reporters Tuesday. "I didn't want to make that mistake again."
The Patriots will have a different look in 2020 after star quarterback Tom Brady left the AFC East franchise in free agency. Dorsett will join quarterback Russell Wilson in Seattle as part of what should be a prolific offense. His speed could prove to be a perfect fit alongside Seahawks wide receivers D.K. Metcalf and Tyler Lockett.
"I just felt like it was the right fit," Dorsett said. "Obviously with 'Schotty' [offensive coordinator Brian Schottenheimer] being there and them bringing in Sanjay [senior offensive assistant Sanjay Lal], I was familiar with a lot of guys on the staff.
"Russell, he's a great quarterback. The way he plays quarterback, the way this offense is fits my skill set."
Dorsett was the No. 29 overall pick in the 2015 NFL Draft. The Miami product spent his first two seasons with the Indianapolis Colts before he was traded to the Patriots in 2017. Dorsett had 29 catches for 397 yards and five touchdowns in 14 games last season for the Patriots.
He won a Super Bowl during his second season with the Patriots. Dorsett also appeared in a Super Bowl during his first season with New England.