He played in Major League Baseball (MLB) for the Oakland Athletics, Cincinnati Reds, San Diego Padres, Los Angeles Dodgers, Seattle Mariners, New York Mets, Philadelphia Phillies, and Atlanta Braves.

He played for the rookie-level Pulaski Rangers in 1999, finishing with a 9–2 record and 2.30 ERA in 16 appearances (10 starts), including one complete game shutout.

During the 2003 season, Harang was traded to the Reds with Joe Valentine and minor leaguer Jeff Bruksch for José Guillén.

[6] In 2006, Harang started on Opening Day for the Reds on April 3 against the Chicago Cubs and allowed 9 runs (6 earned) over 5 innings.

In his third start of the season, Harang pitched 7 shutout innings against the St. Louis Cardinals, facing off against reigning Cy Young Award winner Chris Carpenter.

Harang pitched a complete game shutout against the Milwaukee Brewers on April 23, allowing five hits as the Reds won 11–0.

[15] Harang hit his first career home run on July 24, 2009, a three-run shot to left field off of Randy Wells of the Cubs.

[18][19] In a ceremonial "goodbye," he started the final game of the season against the Brewers, but exited in the third inning with a blister on his finger.

[22] On December 6, 2010, Harang signed a one-year, $3.5 million contract with the San Diego Padres that included a mutual option for 2012.

[26] On April 13, 2012, Harang struck out 9 consecutive batters after giving up a single to set the all time Dodgers record against the San Diego Padres.

[27][28] On June 7, Harang allowed 3 runs in 6 innings in an 8–3 victory over the Philadelphia Phillies to collect his 100th career Major League win.

On April 6, 2013, the Dodgers traded Harang and $4.25 million to cover part of his salary to the Colorado Rockies for catcher Ramón Hernández.

[30] The Rockies designated Harang for assignment and on April 11 traded him and cash to the Seattle Mariners for minor leaguer Steven Hensley.

On September 2, 2013, Harang signed a minor league contract with the New York Mets and assigned to the Triple-A Las Vegas 51s.

[42] On January 5, 2015, Harang signed a one-year, $5 million contract with Philadelphia Phillies that included performance bonuses.

[44][45] After missing most of July with plantar fasciitis in his left foot, Harang ended his final MLB season with a 6–15 record and 4.86 ERA in 29 starts for the Phillies.

[6] Harang's younger brother Darryl pitched in the minor leagues for the Toronto Blue Jays organization from 2004 to 2008 and in the Reds system in 2010.