Drafted by the Tigers, he spent the next several years in their minor league system before making his debut with the team in 2009.

At Tacoma, he tied for fifth in the Pacific Coast League in wins despite only pitching half the season for them; in Seattle, he had a 5–7 record and a 4.83 ERA.

[1][2] He grew up rooting for the Seattle Mariners, listing Ken Griffey Jr., Randy Johnson, and Jay Buhner among his favorite players.

[5] French was selected to play in the inaugural Aflac All-America High School Baseball Classic on August 23, 2003, at Hammond Stadium in Ft. Myers, Florida.

[6] In 11 games (10 starts), he had a 1–3 record, a 2.74 earned run average (ERA), 49 strikeouts, and 19 walks in 49+1⁄3 innings pitched.

[6] His 11 wins tied with three other starters for seventh in the Midwest League, and his 157+1⁄3 innings pitched ranked sixth.

French led the Eastern League with 170 innings pitched and 195 hits allowed, while he tied Brad Bergesen and Magee for the lead with three complete games, finished second with the same amount of losses as four other starters (11, behind Magee's 13), and gave up the fifth-most walks in the league (60, tied for fifth with Kyle Aselton).

[11] French appeared in one more game before being optioned back to Toledo on May 21 after Robertson returned from the disabled list.

[6] He was called up at the end of June, this time to serve as a starter, replacing Alfredo Figaro on the Tigers' roster.

[16][17] It was his only win in seven games (five starts) for the Tigers through the end of July, but French posted a 3.38 ERA in that span.

[12] Though they led the AL Central through the 2009 season's first four months, the Tigers wanted some help for their rotation as they sought to make the playoffs.

[18] On July 31, 2009, French and prospect Mauricio Robles were traded to the Seattle Mariners for Jarrod Washburn.

[19] On August 15, he was the losing pitcher in a 5–2 defeat by the New York Yankees, but all four runs French allowed were unearned, the result of a Franklin Gutiérrez error in the second inning.

[22] He made two relief appearances and started a game on June 14 in place of Ian Snell, who had not been pitching well.

[25] He was briefly recalled on July 9, making a relief appearance against the Yankees before being sent back to Tacoma the next day.

After Ryan Rowland-Smith was placed on the disabled list, French was called up on July 28 to take his spot in the Mariners' rotation.

[23] On August 6, he again beat Greinke and the Royals, limiting Kansas City to one run over eight innings in a 7–1 victory.

His season ended poorly, as he gave up eight runs in four innings on October 1 against the Oakland Athletics in what ESPN called "the worst of his 13 [2010] starts for the Mariners.

[1] French participated in spring training in 2011 for the Mariners, competing for a long relief spot in the bullpen.

[32] On August 13, 2011, French was designated for assignment by the Mariners to allow Wily Mo Peña onto the team's 40-man roster.

"Mike Sweeney and I were talking when he walked up and stood there near us," Griffey recalled French's first day with the team.