Triolo made his professional debut with the West Virginia Black Bears of the Low–A New York–Penn League where he batted .239/ 314/.389 with two home runs and 34 RBIs over sixty games, in which he played 41 games at third base and 17 games at shortstop.[2][8] He did not play a game in 2020 due to the cancellation of the minor league season because of the COVID-19 pandemic.[9] He played the 2021 season with the Greensboro Grasshoppers of the High-A East, slashing .304/.369/.480 with 15 home runs, 42 RBIs, 29 doubles, and 25 stolen bases over 108 games, in which he played 102 games at third base and five games at shortstop.[10] He was awarded a Minor League Gold Glove for his defense at third base.[11] He was assigned to the Altoona Curve of the Double-A Eastern League for the 2022 season.[12] Over 112 games, Triolo slashed .282/.376/.419 with nine home runs, 39 RBIs, and 24 stolen bases, in which he played 87 games at third base, 17 games at shortstop, and seven games in center field.[13][2]
On November 15, 2022, the Pirates selected Triolo's contract and added him to the 40-man roster to protect him from the Rule 5 draft.[14] Triolo was optioned to the Indianapolis Indians of the Triple-A International League to begin the 2023 season.[15] On March 27, 2023, it was announced that Triolo would undergo surgery to address a fractured hamate bone in one of his wrists and miss multiple months in recovery.[16] Once he returned, Triolo played in 41 games split between the Single–A Bradenton Marauders and Indianapolis, hitting a cumulative .309/.412/.463 with one home run, 24 RBI, and eight stolen bases while playing 32 games at third base, 16 games at shortstop, nine games at second base, and three games at first base.[2]
On June 27, 2023, Triolo was promoted to the major leagues for the first time following an injury to Ke'Bryan Hayes. He made his MLB debut the next day versus the San Diego Padres and recorded his first MLB hit, a single.[17] He hit his first MLB home run on August 13, a pinch-hit three run home run at PNC Park, helping lead the Pirates to a 4-2 win over the Cincinnati Reds.[18] Triolo appeared in 54 games for the Pirates during the 2023 season and batted .298/.388/.398 with three home runs and 21 RBI over 181 at-bats.[19]
The Pirates named Triolo to his first Opening Day roster for the 2024 season, and Pirates manager Derek Shelton announced he would be the team's starting second baseman.[20] He spent the entirety of the season with Pittsburgh
and batted .216/.296/.315 with nine home runs and 46 RBI in 394 at-bats. He played 61 games at third base, 47 at second base, nine at shortstop, nine at first base, and one in right field. His defensive efforts earned him the National League Gold Glove Award for utilitymen.[21]
Triolo began the 2025 season on the injured list with a lumbar spine strain.[22] He was activated on April 16 and returned to the Pirates.[23] In July, he was optioned to Indianapolis after hitting .158 over 55 games with Pittsburgh.[24] He was promoted back to the Pirates on August 1.[25] Across 107 games played with the Pirates, Triolo hit .227 with 24 home runs, 39 RBI, and 13 stolen bases.
