Early career Holl attended
Minnetonka High School from 2007 to 2010. In his senior year at Minnetonka High School, Holl was named co-captain alongside
Jake Gardiner and made the honor roll. On November 20, 2009, he signed a commitment agreement with the
Minnesota Golden Gophers at the
University of Minnesota. At the conclusion of the season, Holl was named a finalist for
Minnesota Mr. Hockey, an award given to the best senior high school hockey player in Minnesota.
Collegiate Holl was selected by the
Chicago Blackhawks in the second round, 54th overall, in the
2010 NHL entry draft; however, he kept his commitment to play for the University of Minnesota. While studying at the University of Minnesota, Holl majored in Finance at the
Carlson School of Management. In his first season with the Gophers, he played in 25 games and recorded seven points, including one goal. After his freshman season, he was invited to Team USA's National Junior Evaluation Camp in August. In his sophomore season, Holl's role on the Gophers deviated from defence to offence occasionally throughout the year. After recording three goals and seven points, he was presented with the Gophers Dr. V. George Nagobads Unsung Hero. The next year, Holl helped the Gophers qualify for the 2014 NCAA Frozen Four where he recorded his first collegiate goal that season with 0.6 seconds left in the game to beat North Dakota 2–1. After his senior season, Holl split his time during the 2014–15 season between Chicago's minor league affiliates: the
Indy Fuel of the
ECHL and the
Rockford IceHogs of the
American Hockey League (AHL).
Toronto Maple Leafs Since he never signed an entry-level contract with the Blackhawks, Holl was a free agent and signed an AHL contract with the
Toronto Marlies in 2015. One year later, on July 2, 2016, he signed an NHL entry-level contract with the
Toronto Maple Leafs. He was called up to the NHL on an emergency basis on January 31, 2018, to replace an ill
Ron Hainsey. He made his NHL debut that night in a game against the
New York Islanders. During this game, he scored his first NHL goal to help the Leafs win 5–0. It marked the first time since 1978 that a Maple Leafs defenseman scored in his NHL debut. On February 1, in a game against the
New York Rangers, Holl scored his second NHL goal to become the first Maple Leafs defenseman to score two goals in his first two games. As well, he became only the sixth defenseman in NHL history to score in each of his first two games. Holl continued to succeed in the AHL, setting a new career-high in points and assists during the regular season. During the
2018 Calder Cup playoffs, he recorded 5 points in 20 games to help the Marlies win their first
Calder Cup in franchise history. during the
2018 Calder Cup Final. On July 3, 2018, Holl signed a two-year, $1.35 million contract extension with the Maple Leafs. He attended the Leafs' training camp prior to the
2018–19 season and was named to the opening night roster. He was a healthy scratch for the Leafs' first 12 games of the season, playing in his first game on November 1, against the
Dallas Stars. As a result of injuries and illnesses, Holl replaced
Igor Ozhiganov in the Leafs lineup and recorded his first career assist in a 7–6 win over the
Philadelphia Flyers on March 15, 2019. The following season, Holl entered a bigger role with the Leafs after the firing of
Mike Babcock. He consistently played on one of the Leafs top pairings alongside
Jake Muzzin and later
Travis Dermott due to injuries. In this increased role, he earned his first multi point game on December 11, against the
Vancouver Canucks. He eventually signed a three-year contract extension with the Maple Leafs on December 31, before their game against his hometown team, the Minnesota Wild.
Detroit Red Wings On July 1, 2023, Holl left the Maple Leafs as a free agent and was signed to a three-year, $10.4 million contract with the
Detroit Red Wings.
St. Louis Blues On March 6, 2026, Holl was acquired by the
St. Louis Blues in a trade-deadline deal with the Red Wings, alongside
Dmitri Buchelnikov, a
2026 first-round pick, and a 2026 third-round pick, in exchange for
Justin Faulk. ==Personal life==