Toppin, a 6-foot-9 sophomore, added to an award collection that includes national Player of the Year by The Associated Press. He averaged 20.0 points and 7.5 rebounds per game while shooting 63%.
He is Dayton's first consensus All-American, leading the Flyers to a school-record 29 wins as they finished No. 3 in the final AP Top 25 poll after the NCAA tournament was canceled due to the coronavirus pandemic.
It matched the highest ranking in school history (1956).
Toppin, who announced last week that he would sign with an agent and enter the 2020 NBA draft, is also one of five finalists for the John R. Wooden Award. He is the No. 9 prospect in the ESPN Top 100.
Dayton's Anthony Grant also swept Naismith and AP honors as the national Coach of the Year after the Flyers won their third Atlantic 10 championship in five years.
Oregon's Sabrina Ionescu won the women's award.