Undrafted, Sillinger played collegiate hockey with
Bemidji State University in the
Central Collegiate Hockey Association. He made his professional debut after his four-year career with the Beavers, signing an AHL contract with the Cleveland Monsters at the tail end of the
2021–22 season on March 25, 2022. After two productive seasons with the Monsters, Sillinger was signed to a one-year, two-way contract with NHL affiliate, the Columbus Blue Jackets on July 1, 2024. In the following season, Sillinger continued his tenure on reassignment with the Monsters before he received his first recall by the Blue Jackets and made his NHL debut in a regular season match against the
Seattle Kraken on January 9, 2025. ==Personal life==