[2][3] Willson attended St. Thomas of Villanova Catholic Secondary School in LaSalle, Ontario, near Windsor, and was all-conference three times in football.

[4] After reporting late to camp in 2008 due to his baseball commitments in Canada, Willson redshirted as a true freshman.

Willson's rookie season was capped with a blowout win in Super Bowl XLVIII; he caught two passes for 17 yards in the Seahawks' 43–8 victory over the Denver Broncos.

[10] Willson caught a game-winning 23 yard touchdown pass with less than a minute left in week 8 against the Carolina Panthers.

In that season's playoffs, Willson caught four passes for 68 yards and a touchdown in a divisional round game against the Carolina Panthers.

In Super Bowl XLIX, Willson had no catches as the Seahawks failed to repeat as champions, defeated 28–24 by the New England Patriots, who rallied in the fourth quarter behind quarterback Tom Brady.

[12] After five years in Seattle, Willson signed a one-year, $2.5 million contract with the Detroit Lions on March 21, 2018.

[15] On September 25, 2019, Willson was signed by the Seahawks after they traded tight end Nick Vannett to the Pittsburgh Steelers.

He has also appeared several times as an NFL analyst on Canadian sports television network TSN during the 2022-23 season and playoffs.