The 24-year-old defenseman has 12 points (two goals, 10 assists) in 43 games this season. He could have become a restricted free agent after the season.
"We are very pleased to sign Juuso to a one-year extension," Coyotes general manager Bill Armstrong said. "He is a big (6-foot-2, 205 pounds), strong, two-way defenseman who has been a great addition to our defensive corps. We look forward to having him on our roster next season."
Valimaki was claimed off waivers by Arizona from the Calgary Flames prior to the season.
Selected by Calgary in the first round (No. 16) of the 2017 NHL Draft, Valimaki has 28 points (five goals, 23 assists) in 125 regular-season games with the Coyotes and Flames, and one assist in two Stanley Cup Playoff games.
