Playing for Princeton University, Weisz earned the 2014 Ivy League Men's Basketball Rookie of the Year. On December 7, 2013, he posted his first career double-double with 17 points and 10 rebounds against Fairleigh Dickinson. He earned second-team All-Ivy League recognition in 2015 and 2016. As a sophomore, in 2014–15, he was 6th in the Ivy League in 3-point field goal percentage, 7th in 3-point field goals, and 8th in scoring. As a junior, he served as a tri-captain of the 2015–16 team, led the Ivy League in assist-to-turnover ratio, and was 2nd in the league in assists-per-game, 4th in assists, 6th in 3-point field goals, and 8th in defensive rebounds. Going into his senior year, The Sporting News projected him as Ivy League first team, and Lindy's projected him as Ivy League second team. As a senior, Weisz led Princeton in rebounds, assists, and steals, while coming in 2nd in the league in assist-to-turnover ratio, 5th in 3-point field goals and defensive rebounds, and 10th in total rebounds. In December 2016, he tied the Princeton single-game record for assists in a game, with 13 against Liberty. He posted his career high of 26 points in a February 3, 2017, 69–64 victory over Dartmouth. He served again as a co-captain, and earned Ivy League Men's Basketball Player of the Year recognition. He became the 8th player in Ivy League history to win both the league's Rookie of the Year Award and Player of the Year Award. He was one of two unanimous first-team All-Ivy selections, despite only ranking fourth on Princeton in scoring average. Weisz was included on the National Association of Basketball Coaches Division I All‐District 13 second-team, earned honorable mention on the Associated Press All-America team, and was named to the Jewish Sports Review 2016–17 Men's College Basketball All-American First Team. The 2016–17 Princeton Tigers earned Princeton its first NCAA Division I Men's Basketball Tournament invitation since the 2010–11 team did so. He became the only player in Princeton career history to amass 1,000 points, 500 rebounds, 300 assists, and 200 3-pointers. He ended his college career 2nd in Princeton history in assists, 5th in 3-pointers, and 12th in scoring. His 511 career defensive rebounds were 5th in Ivy League history.
On August 3, 2017, Weisz started his professional career with Hapoel Gilboa Galil of the Israeli Premier League, signing a one-year deal with an option for another one. Weisz helped Gilboa Galil reach the 2018 Israeli League Playoffs, where they eventually lost to Hapoel Jerusalem in the Quarterfinals.
On July 19, 2018, Weisz signed with Maccabi Ashdod for the 2018–19 season. On April 10, 2019, Weisz recorded a career-high 27 points, shooting 6-of-9 from three-point range, along with eight rebounds, six assists and three steals, leading Ashdod to a 94–86 win over his former team Hapoel Gilboa Galil. In 26 games played for Ashdod, he averaged 9.0 points, 3.9 rebounds and 3.7 assists per game.
Hapoel Be'er Sheva (2019–present)
On June 21, 2019, Weisz signed a two-year deal with Hapoel Be'er Sheva. Two months later, he was named Be'er Sheva's new team captain, replacing Chanan Colman. On October 21, 2019, Weisz recorded a season-high 21 points, shooting 5-of-8 from three-point range, along with eight assists, scoring the last 13 out of 15 points to give Be'er Sheva an 88–87 win over Hapoel Eilat.
International play
Weisz was a member of the Under-18 US National team that won the 2013 Maccabiah Games gold medal, along with future NFL player Anthony Firkser, and earned the Most Valuable Player recognition for the tournament. In the final, gold medal game against Team Israel, Weisz scored 19 points, brought down 12 rebounds, and had 11 assists. During the summer of 2015, Weisz was a starter for the Israel national under-20 basketball team at the 2015 FIBA U-20 European Championship, where Israel finished 10th out of 20 teams.
