Biro's time with the Sabres officially ended this off-season when he signed a one-year, two-way deal with the Seattle Kraken. He joined the Sabres organization during the 2020-21 season and spent most of his tenure in the AHL with the Amerks, where he recorded 46 goals and 140 points in 171 games. In his limited time with the Sabres, he played six games and scored two goals.