Tukuafu, who was released by the Seattle Seahawks on June 22, was signed to a two-year contract Thursday by the San Francisco 49ers.
His tryout with the Niners figures to start on Sunday in a preseason game at Indianapolis.
The 6-4, 272-pound Tukuafu, 26, was called upon when San Francisco received a roster exemption for the absent Kentwan Balmer, who has been placed on the NFL's "left squad" list.
Tukuafu, a rookie from Salt Lake City, was Oregon's Most Inspirational and Outstanding Defensive Lineman from the Rose Bowl team of 2009. Over the past three seasons with the Ducks, he totaled 131 tackles, 14 1/2 sacks, five fumble recoveries and four forced fumbles.