After college, den Dekker was selected by the New York Mets in the fifth round of the 2010 Major League Baseball draft.
He made his pro debut that summer with the Gulf Coast League Mets, hitting .278 with five RBIs in five games before being promoted to the Savannah Sand Gnats.
In 2011, den Dekker played for the St. Lucie Mets and Binghamton Mets.
He was invited to spring training in 2012.

In 2013, den Dekker received his third invitation to the Mets Spring training camp.
He played in a career-high 19 games and posted a .205 batting average as he went 9-for-44 with one home run and seven runs batted in while striking out 16 times.
On March 24, den Dekker broke his right wrist attempting to make a play on a fly ball hit by Detroit Tigers outfielder Austin Jackson.

On August 27, the Mets promoted den Dekker to the major leagues.
He made his major league debut on August 29.
He hit his first MLB home run on September 1, off Ross Ohlendorf of the Washington Nationals.
For the season, he batted .207/.270/.276.
After college, den Dekker was selected by the New York Mets in the fifth round of the 2010 Major League Baseball draft. He made his pro debut that summer with the Gulf Coast League Mets, hitting .278 with five RBIs in five games before being promoted to the Savannah Sand Gnats. In 2011, den Dekker played for the St. Lucie Mets and Binghamton Mets. He was invited to spring training in 2012.
In 2013, den Dekker received his third invitation to the Mets Spring training camp. He played in a career-high 19 games and posted a .205 batting average as he went 9-for-44 with one home run and seven runs batted in while striking out 16 times. On March 24, den Dekker broke his right wrist attempting to make a play on a fly ball hit by Detroit Tigers outfielder Austin Jackson.
On August 27, the Mets promoted den Dekker to the major leagues. He made his major league debut on August 29. He hit his first MLB home run on September 1, off Ross Ohlendorf of the Washington Nationals. For the season, he batted .207/.270/.276.
Matt den Dekker