He played in Major League Baseball (MLB) for the Seattle Mariners, Toronto Blue Jays, and Philadelphia Phillies.

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.

[citation needed] 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.

[5][6] 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.

[citation needed] On May 6, 2010, Saunders was recalled from Tacoma after the Mariners put Milton Bradley on the restricted list.

[8] 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.

[15] After the Blue Jays lost 12–3 to the Tampa Bay Rays on April 24, Saunders was activated off the disabled list.

[16] He experienced discomfort in his knee in early May, missing several games after having fluid drained and receiving a cortisone injection.

[8] On January 15, 2016, Saunders and the Blue Jays avoided salary arbitration by agreeing to a one-year, $2.9 million contract.

[32] The Royals released Saunders on March 24,[33] and he signed a minor league contract with the Baltimore Orioles on April 2.

[34] He made 25 appearances for the Triple-A Norfolk Tides, batting .161/.291/.253 with one home run, 14 RBI, and two stolen bases.

Saunders represented Canada at the 2013 World Baseball Classic (WBC) and was named as one of three outfielders on the All-WBC Team for his good offensive performance.

[42] On October 25, 2019, Saunders announced that he would retire following the 2019 WBSC Premier12, and become a minor league coach in the Atlanta Braves organization in 2020.