The 24-year-old defenseman, who was a restricted free agent, had 14 points (seven goals, seven assists) in 70 games with the Avalanche last season and no points in 12 Stanley Cup Playoff games.
He led the NHL in hits (228) for the third straight season and was an NHL career-best plus-19.
"[Zadorov] brings a tough, physical presence to our blue line," Avalanche general manager Joe Sakic said. "He is an important part of our back end and we are excited to have him under contract for next season."
Selected by the Buffalo Sabres with the No. 16 pick in the 2013 NHL Draft, Zadorov has 62 points (18 goals, 44 assists) in 292 regular-season games with the Sabres and Avalanche and three points (one goal, two assists) in 18 playoff games.
