Gilbert was born on October 30, 1996,[1] to parents Dennis Sr. and Kim Gilbert.[2] Growing up, he refused to play hockey year round in order to play lacrosse and football.[3]
Gilbert played collegiate hockey for the Notre Dame Fighting Irish at the University of Notre Dame, originally of Hockey East.[4] In his sophomore season with the Fighting Irish in 2016–17, Gilbert helped guide Notre Dame to the Frozen Four and was announced as the Hockey East's Best Defensive Defenseman and a Hockey East Third Team All-Star.
Gilbert concluded his collegiate career following his junior season with the Fighting Irish in the 2017–18 season, turning professional by signing a three-year, entry-level contract with the Chicago Blackhawks on April 14, 2018.[5]
Following two seasons in Colorado, Gilbert left as a free agent and was signed to a two-year, $1.525 million contract with the Calgary Flames on July 13, 2022.[7]
At the conclusion of his contract with the Flames, Gilbert opted to leave as a free agent and was signed to a one-year, $825,000 contract with hometown club, the Buffalo Sabres, on July 1, 2024.[8]