(MIAA) First Team selection, and twice MIAA All-Conference, as in hockey he played as a defenseman and led the high school to two state championships. He then played college baseball at Radford University, playing 161 games at first base and 6 games in left field. In 2017 as a freshman, Horwitz batted .311/.384/.481, and was named Big South Conference Second Team, and a Collegiate Baseball Freshman All American. In 2018, he batted .288/.386/.443 in 219 at bats, had 43 RBIs (7th in the Conference) and 34 walks (9th; the same as his number of strikeouts), and was again named Big South Conference Second Team. After the 2018 season, he played collegiate summer baseball with the Bourne Braves of the Cape Cod Baseball League. In 2019 he batted .268/.392/.465 in 213 at bats, led the league with 49 walks (against only 29 strikeouts) and 7 sacrifice flies, and had 49 runs (6th) and 10 home runs (7th), and was named Big South Conference Honorable Mention. He was drafted by the Toronto Blue Jays in the 24th round of the 2019 Major League Baseball draft. He signed for a $100,000 signing bonus. Horwitz spent his first professional season in 2019 with the Rookie League Bluefield Blue Jays and Class A- Vancouver Canadians. He batted a combined .307/.368/.440, as in 248 at bats he had 4 home runs, 52 RBIs, stole 5 bases without being caught, and walked 24 times (while striking out 30 times). He played 26 games at first base, 18 games in left field, and two games at second base. With Bluefield, he batted .330 (6th in the Appalachian League), with 18 doubles (3rd), 49 RBIs (3rd), and 3 sacrifice flies (10th). He was named a 2019 Appalachian League All Star. Horwitz did not play for a team in 2020 due to the Minor League Baseball season being cancelled because of the Covid-19 pandemic. He returned in 2021 to play for the now Class A+ Vancouver and for the Class AA New Hampshire Fisher Cats. Horwitz batted a combined .294/.400/.462, as in 405 at bats he had 12 home runs and 66 RBIs, and 70 walks (versus 68 strikeouts). He played 85 games at first base, five games in left field, and one game at second base. With Vancouver, he led the High-A West with 28 doubles and 70 walks (to only 66 strikeouts), and had a .401 on base