He played in Major League Baseball (MLB) for the Cincinnati Reds from 2007 through 2018, the Kansas City Royals and Oakland Athletics in 2019, and the Minnesota Twins in 2020.

[6] Bailey completed his high school career with 41 wins, 4 losses, a 0.98 ERA, and 536 strikeouts in 298 innings pitched.

In 2004, the Cincinnati Reds selected Bailey with the seventh pick in the Major League Baseball amateur draft.

Although he won just three games and lost five, Baseball America named him as the best prospect in the Florida State League.

[8] After he had appeared in 13 games, the Reds promoted Bailey to the Chattanooga Lookouts, their affiliate in the Double-A Southern League.

In that game, Bailey pitched five innings, allowing two runs on five hits and four walks with three strikeouts, and qualifying for the win.

Bailey began the 2009 season with the Triple-A Louisville Bats after failing to earn a spot on the Reds' roster.

On September 28, 2012, Bailey pitched the first no-hitter at PNC Park, and the 15th in Reds history, in a 1–0 road victory over the Pittsburgh Pirates.

[18] Bailey struck out ten on 115 pitches, allowing only one walk to Andrew McCutchen in the seventh, while Pirates shortstop Clint Barmes reached first base on an error by Reds third baseman Scott Rolen in the third inning.

On July 2, 2013, Bailey pitched a 3–0 no-hitter against the San Francisco Giants at Great American Ball Park, besting Tim Lincecum—himself a no-hit pitcher only eleven days later.

Later in that inning, Bailey was bailed out by Joey Votto when Buster Posey hit a sharp ground ball to first.

Bailey became the third Reds pitcher, along with Jim Maloney and Johnny Vander Meer (who'd done it in consecutive starts), to have more than one career no-hitter.

Notably, Bailey threw his no-hitter in the MLB Network Showcase game, with Reds legend Sean Casey in the booth.

On May 1, 2015, it was revealed that his right elbow was diagnosed with a torn UCL, requiring Tommy John surgery, and it prematurely ended his 2015 season.

[23] After many setbacks and rehabilitation, Bailey made his return to the mound for the Reds on July 31, more than a year since his last start.

[25] On September 7, 2018, Bailey was removed from the rotation after suffering 9 straight losses; his record on the season was 1–14 at that point and he had an ERA of 6.09 in 20 starts.

[26] On December 21, 2018, the Reds traded Bailey to the Los Angeles Dodgers, along with Jeter Downs and Josiah Gray, in exchange for Matt Kemp, Yasiel Puig, Alex Wood, Kyle Farmer and cash considerations.

[28] On February 9, 2019, Bailey signed a minor-league contract with the Kansas City Royals that included an invitation to spring training.

On June 22, 2021, Bailey signed a minor league contract with the Athletics organization and was assigned to the Triple-A Las Vegas Aviators.

In May 2021, Bailey was named to the roster of the United States national baseball team for the Americas Qualifying Event.