- Stjernberg played three seasons at Bowling Green State University from 2023 to 2026, recording 37 points (14goals, 23 assists) in 86 career games. He served as an alternate captain during his junior season and led the team's defensemen in goals in 2025–26, scoring six goals in 25 games.
- In March 2026, Stjernberg signed a two-year contract with the Colorado Avalanche, joining the Eagles for the remainder of the 2025–26 season. He brings size, offensive ability from the blue line, and a strong defensive presence, including his ability to block shots, to Colorado's defensive group.
