Joe was considered a borderline draft pick, ranking No. 60 in ESPN's NBA draft rankings.
"I know a lot of people have been waiting to hear my decision, but this has definitely been one not to be rushed," Joe said. "After all things considered, I have decided to play my next season at the University of Arkansas and continue my dream as a hog."
Joe, a 6-foot-5 shooting guard, averaged 16.9 points and 4.1 rebounds last season. However, he missed six games in January and February due to a knee injury. Without Joe in the lineup, Arkansas went 1-5. With a healthy Joe, the Razorbacks were 19-7.
"We are so excited to have Isaiah back," coach Eric Musselman said. "He received incredible feedback from the NBA and got valuable experience with NBA interviews. We know how hard of a decision this was for Isaiah and his family. Zai's goal is to have a long NBA career and we can't wait to continue helping him reach his dream."
Arkansas lost All-SEC guard Mason Jones to the NBA draft earlier this offseason, but the Razorbacks are reloading with one of the nation's top recruiting classes and three graduate transfers. ESPN 100 recruits Moses Moody, KK Robinson, Davonte Davis and Jaylin Williams are entering the fold, while transfers Jalen Tate (Northern Kentucky), Vance Jackson (New Mexico) and Justin Smith (Indiana) signed in the spring.
Musselman also had transfers J.D. Notae (Jacksonville), Abayomi Iyiola (Stetson) and Connor Vanover (California) sitting out last season. Joe and guard Desi Sills (10.6 PPG) are the lone returning starters.
Arkansas was ranked No. 25 in ESPN's Way-Too-Early Preseason Top 25.