Smart chose the Tigers out of a final six that included Kansas, Kentucky, Oklahoma State, UCLA and Florida.
"It's best for me," Smart told ESPN. "I think I'll get a lot better. I just want to work on my game and I think that they'll prepare me for my future."
Smart, a 6-4 point guard from Scotlandville Magnet High School in Baton Rouge, Louisiana, has been considered one of the top prospects in the 2018 class since early in his high school career. He's currently ranked No. 27 in the ESPN 100, slotting in as the No. 6 point guard in the class.
Smart had a solid spring with the Houston Hoops AAU program, averaging 15.1 points and 4.2 assists while shooting 40 percent from 3-point range on the Nike EYBL circuit.
Landing Smart is a major early statement for LSU coach Will Wade, who took over for Johnny Jones in March. Wade is hoping to keep the best talent in the state from leaving Louisiana, and pulling Smart away from stiff competition followed that objective.
Wade is hoping the good news continues this weekend, as five-star forward Nazreon Reid is on an official visit to Baton Rouge.