Dellandrea was drafted in the first round, fifth overall, by the Flint Firebirds in the 2016 OHL Priority Selection. He appeared in his first career OHL game on September 21, 2016, scoring a goal against Brendan Bonello of the Saginaw Spirit 63 seconds into the game, as the Firebirds defeated the Spirit 4-0. He began his OHL career with points in each of his first five games. On October 15, Dellandrea scored his first career OHL multi-goal game, as he had two goals and added an assist in a 5-3 loss to the Barrie Colts. Dellandrea finished the 2016-17 season with 13 goals and 24 points in 57 games. On March 23, Dellandrea suited up for his first career post-season game, as he was held off the score sheet in a 5-2 loss to the Sault Ste. Marie Greyhounds. Six days later, Dellandrea earned his first career OHL playoff point, assisting on a goal scored by Kole Sherwood in a 5-2 loss to the Sault Ste. Marie Greyhounds. In five playoff games, Dellandrea earned an assist. Dellandrea saw a dramatic improvement to his offensive numbers during the 2017-18 season. In his first game of the season on September 22, Dellandrea scored two goals in a 5-3 win over the Kitchener Rangers. On November 15, he recorded his second career three-point game, as Dellandrea recorded three assists in a 5-3 win over the Saginaw Spirit. Dellandrea recorded his first career OHL hat-trick on December 16, as he scored three goals, as well as added two assists for a five point game, in a 5-2 win over the Sarnia Sting. From January 26 until February 2, Dellandrea recorded four consecutive two-point games. Dellandrea finished the season with 27 goals and 59 points in 62 games. Following the season, Dellandrea was named the Firebirds MVP and awarded the Combined Academic & Athletics Excellence award, having earned a 4.0 grade point average while attending Grand Blanc High School. Dellandrea returned to the Firebirds for the 2018-19 season, as he was named captain of the team. On January 6, Dellandrea set a career high as he recorded four assists in a 6-4 win over the Sault Ste. Marie Greyhounds. Less than a week later, on January 12, Dellandrea tied his career high for points in a game, as he scored a goal and four assists for five points, in a 6-2 victory over the Sarnia Sting. Dellandrea finished the season with 22 goals and 63 points in 60 games. In 2019-20, Dellandrea returned to Flint for a fourth season, remaining the captain of the team. On November 20, Dellandrea recorded the second hat-trick of his OHL career, as he scored three goals in a 6-4 loss to the Sarnia Sting. Just over two weeks later, on December 5, Dellandrea recorded another hat-trick, as he scored three goals, and added an assist, in a 5-2 win over the Barrie Colts. On January 19, Dellandrea tied his career-high for points in a game, as he scored two goals and added three assists for five points, in a 8-5 win over the Kingston Frontenacs. This game started a five-game streak in which Dellandrea scored 10 goals and 18 points. Dellandrea finished the season with a career-high 32 goals and 70 points in 48 games.
Professional
Dallas Stars
Dellandrea became the first Firebird to be selected in first round of the NHL Entry Draft when he was selected 13th overall by the Dallas Stars in 2018. He then participated at the Stars Development camp, and signed a three-year entry-level contract with the Stars on September 19, 2018. On March 19, 2019, following the end of his junior season with the Flint Firebirds, the Stars assigned Dellandrea to their American Hockey League affiliate, the Texas Stars. The following day, on March 20, Dellandrea appeared in his first professional hockey game, as he was held without a point in a 6-3 victory over the Grand Rapids Griffins. On April 5, Dellandrea scored his first career professional goal, as he scored the game winning goal on a penalty shot against Collin Delia of the Rockford IceHogs in a 2-1 win. Dellandrea also assisted on the first goal of the game to earn his first career multi-point game in the AHL. In 11 games with Texas, Dellandrea scored two goals and three points.
International play
On April 19, 2018, Dellandrea was named an assistant captain for Team Canada at the 2018 IIHF World U18 Championships. Team Canada placed fifth in the tournament and Dellandrea ended with two goals and five points. Dellandrea played for Team Canada at the 2020 World Junior Ice Hockey Championships, as he scored three goals and five points in seven games, helping Canada win the gold medal.
Personal life
Dellandrea was born in Port Perry, Ontario, to Loni and Jay Dellandrea. He has one younger sister, Tris. In December 2017, Dellandrea was diagnosed with Celiac disease and requires a gluten free diet to remain healthy. He grew up in Port Perry and played some of his minor hockey for the Port Perry Predators before moving to the Central Ontario Wolves.
