He played in Major League Baseball (MLB) for the Kansas City Royals, Colorado Rockies, St. Louis Cardinals, Washington Nationals, Arizona Diamondbacks, and Texas Rangers.

[1] Holland began his professional career in 2007, making 22 relief appearances for the Idaho Falls Chukars of the Rookie-level Pioneer League, and going 6–1 with a 3.48 ERA, striking out 37 batters in 332⁄3 innings.

In 2008, he pitched for the Wilmington Blue Rocks of the Class A-Advanced Carolina League, going 4–5 with a 3.42 ERA in 32 games (seven starts), fanning 96 batters in 841⁄3 innings.

He was promoted to the majors on July 29, 2010, and made 15 relief appearances for the Kansas City Royals, going 0–1 with 23 strikeouts and a 6.75 ERA in 182⁄3 innings.

[2] Holland started the 2011 season in Omaha, but was called up again in May, earning his first major league win in a May 19 game against the Texas Rangers.

He assumed closing duties when Jonathan Broxton, who began the season as the team's closer, was traded to the Cincinnati Reds on July 31.

On October 22, Holland won the inaugural Mariano Rivera Award for his outstanding performance as a closer.

[7] After serving the bulk of the 2015 season as the Royals' closer, compiling 32 saves with a 3.83 ERA, doctors discovered in late September that Holland had a "significant tear" in his right ulnar collateral ligament.

[8] With the Royals finishing the season 95–67, the team won the 2015 World Series against the New York Mets, their first title in 30 years.

[10] On April 3, he earned his first save since September 17, 2015, defeating the Milwaukee Brewers on his Rockies debut and Opening Day.

[12] On Mother's Day, Holland broke the Rockies franchise record of converting 16 consecutive saves to start a season, formerly held by José Jiménez, which he had set in 2002.

Memorably, on July 2, Holland entered in the bottom of the ninth at Dodger Stadium with the Diamondbacks holding a 4–3 lead.

With the bases still loaded, Holland was replaced on the mound by T. J. McFarland, who promptly walked Cody Bellinger he faced to lose the game.

He allowed a leadoff double to Garrett Cooper, walked Neil Walker, and gave up a single to Starlin Castro which loaded the bases with nobody out.

Following the blown save, manager Torey Lovullo announced Holland would no longer serve as the Diamondbacks' closer.

On August 13, 2019, Holland signed a minor league contract with the Washington Nationals and was assigned to the Double–A Harrisburg Senators.

With the 2020 Kansas City Royals, Holland appeared in 28 games, compiling a 3–0 record with 1.91 ERA and 31 strikeouts in 28+1⁄3 innings pitched.

[35] Holland's departure from the Rangers came shortly after he accrued ten years of major league service time.