Viro signed a three-year, entry-level contract with the Red Wings on Wednesday, per CapFriendly.
Viro racked up 14 points in 53 games with TPS of the Finnish Liiga. The 19-year-old defenseman was selected by the Red Wings in the third round of the 2020 draft. He could make the jump to North America in 2021-22, but he's unlikely to play at a higher level than AHL Grand Rapids.