Taking his place on the roster is much-traveled OF/DH Wily Mo Pena. He was selected from Triple-A Tacoma and was in uniform for Saturday's game against the Boston Red Sox, one of four teams Pena has played for in his career.
Smoak was hit in the face by a bad-hop grounder in the second inning of Friday's game. X-rays revealed the fracture and a CT scan also showed a hairline fracture of the maxilla bone in his left cheek.
The Mariners first baseman will be restricted from activity for three to five days, then may resume playing catch and taking batting practice.
He has appeared in a career-high 101 games, hitting .220 with 30 runs scored, 23 doubles, 12 home runs and 40 RBIs. Smoak had recently missed seven games from Aug. 3-10 because of a sore right thumb.
"I was hopeful it was just the nose. But it's a little bit more than that," Mariners manager Eric Wedge said. "He's got a fracture underneath the eye, too. But the good news is it's nothing too serious, but we'll still have to give him some time. He's going to get another opinion. In fact, he's on his way there right now to get another opinion. After that we'll have a better idea on the timeline."
Smoak was acquired from Texas last season at the trading deadline in the deal that sent left-hander Cliff Lee to the Rangers.
Pena, who hit .333 with 11 runs, four doubles, four home runs, 14 RBIs in 13 games for Tacoma, started the season between Triple-A Reno and the Arizona Diamondbacks before being designated for assignment on July 15.
He spent parts of eight big-league seasons with the Red Sox, Reds, Nationals and Diamondbacks. He is a career .251 hitter with 82 home runs, 67 doubles, and 232 RBIs in 577 games. He has also hit 104 career minor league home runs.
To make room on the 40-man roster, the Mariners designated LHP Luke French for assignment. He was 8-8, 6.12 ERA in 23 starts for Tacoma.