[5] His best season in Japan came in 2009 when he posted a 1.54 earned run average (ERA) to lead the league.

Coming out of spring training, Chen won the number two spot in the Orioles' starting rotation behind Jason Hammel.

[15] In his return from the disabled list on July 10, 2013, Chen pitched seven innings in a matchup against the Texas Rangers striking out four and allowing three hits, earning the win.

He dedicated the win to victims of the 2014 Kaohsiung gas explosions, which occurred hours earlier in his hometown.

[17] On September 10, Chen picked up his 15th win of the season against the Boston Red Sox and carried a perfect game into the sixth inning until Dan Butler's first major league hit.

[20] On June 26, 2015, Chen became the second Taiwanese-born player to have 100 career starts in the major leagues (after Chien-Ming Wang), allowing two runs and striking out five over six innings in a no decision against the Cleveland Indians.

[22][23] On January 13, 2016, Chen agreed to a five-year contract worth US$80 million with the Miami Marlins.

[24] On January 25, 2017, Chen was announced as the cover athlete for the Taiwanese version of MLB The Show 17.

[25] In his first season as a Marlin, Chen went 5–5 in 22 starts after spending some time on the disabled list with an injury.

On July 24, Chen hit his first major league double, off Atlanta Braves' starter Julio Teherán.

[33] He made only two appearances for the main club, logging a 1–0 record and 3.86 ERA with 7 strikeouts across 9+1⁄3 innings pitched.

On April 2, 2024, Chen signed with the Long Island Ducks of the Atlantic League of Professional Baseball.

"[41] In 2012, Chen started a baseball scholarship program for Taiwanese students, contributing funds based on statistical milestones reached per season.