In 2016, Hayes spent the season with the West Virginia Power, where he earned South Atlantic League All-Star honors[7] and compiled a .263 average, with six home runs, and 37 RBI, in 65 games. In 2017, Hayes moved up with the Bradenton Marauders, where he batted .278, with two home runs, and 43 RBI, in 108 games[8] and was named a Florida State League All-Star.[9]
On July 19, 2020, it was announced that Hayes had tested positive for COVID-19. On September 1, 2020, the Pirates promoted him to the majors.[17] Making his MLB debut the same day, he hit his first career home run against the Chicago Cubs.[18] Hayes received five votes in 2020 National League Rookie of the Year voting, finishing in sixth place.[19]
In his 2021 season debut against the Cubs, Hayes hit a home run in his first at bat of the season. On April 4, 2021, Hayes was placed on the 10-day injured list due to left wrist inflammation after leaving a game the previous day because of the injury.[20] On May 9, Hayes was placed on the 60-day injured list.[21] He was activated on June 3.[22] On June 11, Hayes became the quickest Pirate to 20 career extra-base hits in the modern era, one game faster than Barry Bonds.
Hayes finished the 2021 season batting .257/.316/.373 with 6 home runs, 38 RBIs and 9 stolen bases in 96 games. He was awarded the Fielding Bible Award for excellent defense as a third baseman.[23]
On April 7, 2022, Hayes agreed to an eight-year, $70 million contract extension with the Pirates, which became official on April 12.[24]
On November 5, 2023, Hayes won the Rawlings Gold Glove Award for NL third basemen, dethroning Nolan Arenado (who had a 10 year streak).