The Seattle Mariners selected Saunders in the 11th round of the 2004 MLB draft.
He then spent the 2005 season with the Everett AquaSox of the Short Season-A Northwest League, hitting .270 with seven home runs and 39 runs batted in (RBI).
In 2006, he was promoted to the Wisconsin Timber Rattlers of the Class-A Midwest League, hitting .239 with four home runs and 39 RBI.
Despite struggling in 2006, for 2007 he was promoted to the High Desert Mavericks of the Advanced-A California League, where he excelled, hitting .299 with 14 home runs and 77 RBI, before he was called up to the West Tenn Diamond Jaxx of the Double-A Southern League, where he finished off the season hitting .288 with one home run and seven RBI in 15 games.
Saunders started the 2008 season once again in West Tenn, where he hit .290 with eight home runs and 30 RBI in 67 games before being promoted to the Tacoma Rainiers of the Triple-A Pacific Coast League on June 17.

After beginning the 2009 season with the Rainiers where he hit .313 with 13 home runs and 32 RBI in 243 at-bats, Saunders was promoted from Tacoma on July 25, 2009, when the Mariners designated Wladimir Balentien for assignment.
 He made his MLB debut that day in a game against the Cleveland Indians at Safeco Field, where he went hitless against Jeremy Sowers in the Mariners 10–3 loss.
 His first MLB hit was a single off of Cliff Lee on July 26, 2009.

On May 6, 2010, Saunders was recalled from Tacoma after the Mariners put Milton Bradley on the restricted list.
Three days later, he hit his first MLB home run off Angels pitcher Ervin Santana.
He finished the 2010 season with a .211 batting average, 10 home runs, and 33 RBI.
Saunders played only 58 games for the Mariners in 2011, and batted .149 with just two home runs and eight RBI.

In 2012, Saunders played a career-high 139 games and greatly improved upon his 2011 campaign.
He hit .247 with 19 home runs and 57 RBI.
He played in 132 games the following season.
Saunders finished 2013 with a .236 batting average, 12 home runs, and 46 RBI.
In 2014, Saunders battled a number of injuries that limited him to 78 games, but finished with a career-high .273 average with 8 home runs and 34 RBI.
The Seattle Mariners selected Saunders in the 11th round of the 2004 MLB draft. He then spent the 2005 season with the Everett AquaSox of the Short Season-A Northwest League, hitting .270 with seven home runs and 39 runs batted in (RBI). In 2006, he was promoted to the Wisconsin Timber Rattlers of the Class-A Midwest League, hitting .239 with four home runs and 39 RBI. Despite struggling in 2006, for 2007 he was promoted to the High Desert Mavericks of the Advanced-A California League, where he excelled, hitting .299 with 14 home runs and 77 RBI, before he was called up to the West Tenn Diamond Jaxx of the Double-A Southern League, where he finished off the season hitting .288 with one home run and seven RBI in 15 games. Saunders started the 2008 season once again in West Tenn, where he hit .290 with eight home runs and 30 RBI in 67 games before being promoted to the Tacoma Rainiers of the Triple-A Pacific Coast League on June 17.
After beginning the 2009 season with the Rainiers where he hit .313 with 13 home runs and 32 RBI in 243 at-bats, Saunders was promoted from Tacoma on July 25, 2009, when the Mariners designated Wladimir Balentien for assignment.  He made his MLB debut that day in a game against the Cleveland Indians at Safeco Field, where he went hitless against Jeremy Sowers in the Mariners 10–3 loss.  His first MLB hit was a single off of Cliff Lee on July 26, 2009.
On May 6, 2010, Saunders was recalled from Tacoma after the Mariners put Milton Bradley on the restricted list. Three days later, he hit his first MLB home run off Angels pitcher Ervin Santana. He finished the 2010 season with a .211 batting average, 10 home runs, and 33 RBI. Saunders played only 58 games for the Mariners in 2011, and batted .149 with just two home runs and eight RBI.
In 2012, Saunders played a career-high 139 games and greatly improved upon his 2011 campaign. He hit .247 with 19 home runs and 57 RBI. He played in 132 games the following season. Saunders finished 2013 with a .236 batting average, 12 home runs, and 46 RBI. In 2014, Saunders battled a number of injuries that limited him to 78 games, but finished with a career-high .273 average with 8 home runs and 34 RBI.
Michael Saunders