Undrafted, Caggiula played junior hockey in Ontario with the Stouffville Spirit of the Ontario Junior Hockey League before enrolling to play college hockey for the University of North Dakota of the NCAA. Although Caggiula was drafted by the major junior hockey team, the Erie Otters in the Ontario Hockey League, he was not convinced he could play in the league. As a result, Caggiula accepted a scholarship to play at North Dakota. In his freshman year at North Dakota, while majoring in kinesiology, Caggiula played in 39 games and ranked second among the team’s rookies in points, goals, and assists. The following season, Caggiula participated in the 2014 Frozen Four, where North Dakota lost 2–1 against Minnesota. Prior to his junior year at North Dakota, Caggiula was invited and participated in the Buffalo Sabres 2014 Development camp. At the conclusion of his junior year, Caggiula was named to the NCHC Second All-Star Team. In his senior season with North Dakota in 2015–16, Caggiula led North Dakota to win the 2016 NCAA championship and was named Most Outstanding Player of the tournament. He was also named to the Second-Team All-American West and to the NCHC First All-Star Team. Following the end of the season, Caggiula gained attention from numerous NHL teams as the top available collegiate free agent. On May 7, 2016, Caggiula agreed to a two-year entry-level deal with the Edmonton Oilers. Although Caggiula was expected to make his debut on October 12, it was delayed due to an injury. His debut eventually came on November 19 in a 5–2 win over the Dallas Stars. Caggiula scored his first NHL goal on December 3, 2016 in an Oilers overtime win over the Anaheim Ducks. On June 14, 2018, Caggiula re-signed with the Oilers on a two year contract. During the 2018–19 season, Caggiula suffered a hand injury during a game against the St. Louis Blues and was placed on injured reserve. At the time of the injury, Caggiula had recorded 10 points in 23 games. On December 30, 2018, Caggiula was traded by the Oilers along with Jason Garrison to the Chicago Blackhawks in exchange for Brandon Manning and Robin Norell. On February 1, 2019, Caggiula scored his first goal as a Blackhawk in a 7–3 win against the Buffalo Sabres.
