Major junior

Amadio was a prolific scorer playing in Northern Ontario's bantam and midget levels, before he was selected by the Brampton Battalion, 36th overall in the 2012 Ontario Hockey League Priority Selection. He played two seasons with the Battalion, through their relocation to North Bay, before he was selected with the last pick in the third-round of the 2014 NHL Entry Draft by the Los Angeles Kings.^[1]

During the 2015–16 season, Amadio scored a franchise record of 50 goals and was nominated for the Red Tilson Trophy and William Hanley Trophy.^[2] Amadio was named the winner of the William Hanley Trophy on April 22, 2016,^[3] and was later selected for the OHL Second All-Star Team.^[4]

Professional

On March 13, 2016, Amadio was signed by the Kings to a three-year, entry-level contract.^[5] He was then reassigned to join their American Hockey League (AHL) affiliate, the Ontario Reign for their playoff run following the 2015–16 season. In 11 post-season games he contributed with 1 goal and 5 points. After beginning the 2017–18 season with the Reign, Amadio received his first recall to the Kings on October 26, 2017.^[6][7] He made his NHL debut that night in a 4–0 shutout victory over the Montreal Canadiens.^[8] In his fourth game, Amadio registered his first NHL goal, scoring in a 5–3 victory over the Toronto Maple Leafs on November 2, 2017.^[9][10] After attending the Kings training camp, Amadio was named to their NHL roster to begin the 2018–19 season.^[11] After playing in 28 games, Amadio was reassigned to the Ontario Reign.^[12] Despite recalls throughout the season, he was again assigned to the Ontario Reign after the Kings failed to clinch a post season berth.^[13]

On March 29, 2021, during his fifth season within the Kings organization in the shortened 2020–21 campaign, Amadio was traded to the Ottawa Senators in exchange for Christian Wolanin.^[14] He made 5 appearances with the Senators following the trade, registering 1 assist.

As a free agent at the conclusion of his contract with the Senators, Amadio was signed to a one-year, two-way contract with the Toronto Maple Leafs on July 29, 2021.^[15] Amadio made the Maple Leafs opening night roster to commence the 2021–22 season, going without a point in 3 games on the fourth line.

On October 29, 2021, Amadio was placed on waivers by the Maple Leafs and claimed the following day by the Vegas Golden Knights.^[16] On January 30, 2022, the Golden Knights signed Amadio to a two-year, $1.525 million contract extension.^[17] Amadio scored the game winning second overtime goal in Game 3 of the first round against the Winnipeg Jets on April 22, 2023.^[18] Amadio finished the playoffs with 5 goals and 10 points including a goal in the series-clinching Game 5 of the 2023 Stanley Cup Finals, where the Golden Knights won the Stanley Cup.^[19]

On July 19, 2023, Amadio was awarded the key to the city of Sault Ste. Marie by Mayor Matthew Shoemaker.^[20]