The Orioles promoted Hays to the major leagues on September 5, 2017, making him the first 2016 draftee to reach the major leagues.[11] He made his major league debut September 7, 2017.[12] He had his first MLB hit, followed by his first MLB home run, in a 9–3 loss against the New York Yankees on September 16.[13] In 20 games for Baltimore during the 2017 season, he batted .217/.238/.317 in 60 at bats.[14] He began 2018 with Bowie. He did not play in the majors in 2018 struggling with under performance and injury.
Hays was recalled by the Orioles from the Triple-ANorfolk Tides on September 7, 2019. He was supposed to have reported to the Surprise Saguaros on September 11, the first time ever that the Arizona Fall League (AFL) season opened before October. His promotion was made possible by both MLB and the Major League Baseball Players Association (MLBPA) which, two days prior to the transaction, approved a rule change that allowed players on the 40-man roster to report to the AFL in October.[15][16] In a 15-inning 11–10 loss to the Toronto Blue Jays at Rogers Centre on September 23, he became the first MLB rookie to have at least five RBIs, a stolen base and an outfield assist in the same game since the RBI became an official stat in 1920.[17] The Orioles eventually decided not to send him to the Saguaros after he started in 15 of 20 games, batted .313 with a .958 OPS and made several spectacular defensive plays. On August 11, 2020, Hays hit a two-run inside-the-park home run against the Philadelphia Phillies to break an 8-8 tie. That would be the game's difference maker as the Orioles won the game in extra innings, 10-9.[18]
In 2020 for the Orioles, Hays slashed .279/.328/.393 with four home runs and nine RBIs; in 2021, he appeared in 131 games with Baltimore, batting .256 with 22 home runs and 71 RBIs.[19]
On January 13, 2023, Hays agreed to a one-year, $3.2 million contract with the Orioles, avoiding salary arbitration.[23] He got five hits in a 9–8 away loss to the Boston Red Sox in the second game of the season on April 1.[24] He had his first four-hit game of the campaign ten nights later in a 12–8 home win over the Oakland Athletics on April 11.[25] Hays was named to the All-Star Game in 2023 after a stellar first half that saw him hit .314/.355/.498 with 9 home runs and 36 RBI in 78 games. He was named the starting center fielder for the game, replacing Mike Trout, who withdrew due to injury.[26] He added two more four-hit games in a pair of road victories after the All-Star break, the first was 6–1 over the Toronto Blue Jays on August 3 followed one month later by 10–3 over the Los Angeles Angels on September 6 in which he also had a season-high four RBI.[27][28]
Hays was sidelined from April 22 to May 13, 2024, because of a strained left calf.[29]
Personal life
Hays and his wife Samantha have two sons together.[30]