Blakeney announced his decision on ESPNU.
"It was my relationship with the coaches and the plan they have for the program," he said. "They've only been there a few years, but it's up and coming. It's a football school, but they're trying to change the culture. I want to be a part of that."
Blakeney chose the Tigers over finalists Kentucky and Missouri, although North Carolina, NC State, Oregon and others had been involved since his decommitment from Louisville in September. Blakeney had committed to the Cardinals on Sept. 4, only to turn around and reopen his recruitment less than two weeks later.
The 6-foot-4 shooting guard from Oak Ridge (Florida) is ranked No. 14 in the ESPN 100, slotting in as the second-best player at his position. He's an explosive scorer who will give coach Johnny Jones and the Tigers a go-to scoring threat on the perimeter. Last month, Blakeney totaled 69 points in two games at the National High School Hoops Festival, including a 36-point, nine-rebound, three-assist performance against Martin Luther King (Pennsylvania).
Blakeney joins overall No. 1 prospect Ben Simmons in LSU's 2015 class. The two stars played AAU ball together in the Each 1 Teach 1 program, with Blakeney averaging 19.5 points and shooting 44 percent from the field on the Nike EYBL circuit.
"It factored in a lot," Blakeney said of his relationship with Simmons. "I know how good he is, how good he can make a team. Me and him together can take a lot of stress off each other on the court. We have good chemistry on and off the court."
Jones has now landed three five-star players since taking over in Baton Rouge in the spring of 2012. Forward Jarrell Martin signed back in the 2013 class.
LSU's 2015 class now ranks No. 6 in the country.