The 6-foot-10 Osunniyi averaged 11.3 points and 7.5 rebounds and ranked eighth nationally with 2.9 blocks for St. Bonaventure last season. He has one season of eligibility.
Osunniyi is the Bonnies' career blocks leader and was a member of the Atlantic 10 all-defensive team four straight years. He blocked at least one shot in 29 of 31 games, including 19 with three or more.
Osunniyi is the second former St. Bonaventure player to transfer to Iowa State. The other is guard Jaren Holmes, who was the Bonnies' second-leading scorer.