TheNew York Yankees selected Jagielo in the first round of the2013 Major League Baseball draft.[6][7] He signed and made his professional debut that season for theStaten Island Yankees.[8] In 54 games, he hit .268/.381/.458 with six home runs. He was named the Player of the Week of theNew York-Penn League for the week of August 19 and was a Mid-Season All-Star.[9] In 2014, Jagielo was ranked as the team's 5th best prospect by MLB.com.[10] He played for theTampa Yankees that year, and hit .259 with a .354on-base percentage, 16 home runs, and 54 RBIs in 85 games and was aFlorida State League Mid-Season All-Star.[9] In an instructional game after the season, Jagielo was hit in the face by a pitch, breaking thezygomatic arch near his left eye, which required surgery.[11]
In 2015, he was ranked as the 8th and 11th best prospect in the system by MLB.com andBaseball America, respectively. He spent the season with theTrenton Thunder, batting .284 with nine home runs and 35 RBIs in 58 games and was anEastern League Mid-Season All-Star.[9] Jagielo suffered a knee injury sliding into home on June 16 and missed the rest of the season.[12] He underwent surgery in July and was expected to play in theArizona Fall League that fall before the Yankees decided to against it.[13]
On December 28, 2015, the Yankees traded Jagielo,Rookie Davis,Tony Renda, andCaleb Cotham to theCincinnati Reds in exchange forAroldis Chapman.[14] Before the 2016 season, MLB.com ranked him as the Reds' 14th best prospect and top power hitter.[15][16] Jagielo spent the season with thePensacola Blue Wahoos, where he batted .205 with seven home runs and 26 RBIs in 111 games.[17] In 2017, he played for both Pensacola and theLouisville Bats, posting a .204 batting average with five home runs and 25 RBIs in 103 total games.[18][19]
