Smart is the first unanimous preseason All-American since Ohio State's Jared Sullinger in 2011-12.
He averaged 15.4 points, 5.8 rebounds, 4.2 assists and 3.0 steals last season for the Cowboys while being recognized as the Big 12 Player of the Year.
The OSU sophomore is joined on the preseason All-America team by Doug McDermott of Creighton, Russ Smith of Louisville, Mitch McGary of Michigan and freshman Andrew Wiggins of Kansas.
The Cowboys open the season Friday night against Mississippi Valley State at Gallagher-Iba Arena. Tip-off is scheduled for 7 p.m.