Ray pitched in one game for the Vermont Lake Monsters in 2010, striking out two in one inning pitched. Pitching for the Hagerstown Suns in 2011, he went 2–3 with a 3.13 earned run average with 95 strikeouts in 89 innings pitched. Ray struggled pitching for the Potomac Nationals in 2012, going 4–12 with a 6.56 ERA.  He returned to Potomac for the start of the 2013 season. After going 6–3 with a 3.11 ERA and 100 strikeouts in 84 innings, he was promoted to the Double-A Harrisburg Senators.  He posted a 5–2 record with a 3.72 ERA at Harrisburg.
Ray started the 2014 season with the Triple-A Toledo Mud Hens. The Tigers announced he would be called up to the Major League team following an April 26 injury to starter Aníbal Sánchez. Ray made his Major League debut on May 6, 2014, earning his first big-league win in the Tigers' 11–4 victory over the Houston Astros.  On August 12, he was recalled to replace an injured Aníbal Sánchez again. Ray pitched five innings, allowing four runs on six hits, while striking out five and walking two, in a 4–2 loss to the Pittsburgh Pirates. 
On December 5, 2014, the Tigers traded Ray and Domingo Leyba to the Arizona Diamondbacks in a three-team trade that brought Shane Greene to the Detroit Tigers, and Didi Gregorius to the New York Yankees.  He started the 2015 season at their AAA affiliate, the Reno Aces.  He made his debut in a Diamondbacks uniform on May 6, 2015, being called up to face the Colorado Rockies in the second game of a doubleheader.  Robbie Ray hit his first career home run on June 7, 2016, off of Chris Archer, becoming the first Diamondbacks pitcher to do so since Wade Miley. Despite striking out 218 batters, Ray finished 8-15 with a 4.90 ERA in 174⅓ innings in 32 starts, giving up 24 home runs and recording just 10 quality starts in 32 total starts.
In his first month and a half of 2017, Ray pitched poorly, recording a 4.57 ERA in 8 starts. In his following 8 starts, however, he went 6-1 with a 1.81 ERA in 54⅔ innings, holding opponents to a .173 batting average. He pitched his first career complete game shutout on May 30 against the Pirates, striking out 10 while allowing just four hits. In his next two starts he struck out 11 and 12 batters respectively. In a five start stretch (those three and the two prior to the shutout), Ray went 5-0 with an 0.24 ERA (1 ER in 37 innings) holding opponents to a .115 batting average (just 14 hits allowed) and 48 strikeouts. On July 2, Ray was named to his first career All-Star game. At the time, he had a 8-4 record and a 3.06 ERA in 100 innings, with a .202 batting average against and 128 strikeouts. On September 4, 2017, Ray struck out a career high 14 batters while pitching 7 2/3 innings in a 13-0 victory against the Los Angeles Dodgers. Ray earned his 12th victory of the season, and this would propel the Diamondbacks to their 11th consecutive victory. He finished the season with 15-5 with 218 strikeouts and a 2.89 ERA over 162 innings in 28 starts. His 12.11 K/9 rate was the best in the National League and he held opponents to a .199 batting average.
Ray throws a fastball in the 92-95 MPH range (tops out at 98 MPH). His primary offspeed pitches are a slider that averages about 85 MPH (tops out at 87 MPH) and a curveball that he throws at about 84 MPH.