At the conclusion of the season, O'Brien left the Devils organization as a free agent. On July 1, 2016, he signed a one-year, two-way contract to join the Colorado Avalanche. O'Brien was assigned to bolster AHL affiliate, the San Antonio Rampage for the 2016–17 season. Hampered by injury throughout the campaign, O'Brien was unable to continue his scoring pace with the Rampage, collecting 9 goals and 24 points in 53 games. He was briefly recalled by the Avalanche, but was returned to the AHL without appearing for the club.