Diallo picked Rutgers after Greg Whittington did not enroll for January and a space opened in the post.
"It was really exciting because everybody knows about coach Eddie Jordan," Diallo said. "He's a great coach, and I can't wait for him to be my coach. It was great to call him and tell him that I was committing to his school. It was a big moment for me."
Diallo was an official visit for a November loss to William & Mary. Freshman Junior Etou, now entrenched as a starter, was his host.
"I liked the team and the school, and especially I liked coach Jordan," Diallo said. "I like the way he coaches. I liked the players and the staff and everything. I really felt comfortable like it was my home."
The 2014 commit will sign this spring and enroll for summer classes.
"I'm really excited for this," Diallo said. "I feel like I have a good opportunity to succeed in basketball and in the classroom. I feel like this is going to be a good experience.
"It's most definitely a burden off my shoulders. Everybody has questions about where they are going to go, and now I can say that I'm more focused on what's next. I'm happy."
"I think I will be good to play for the Big Ten," he said. "I'm a defense guy with rebounding and blocked shots. Also, on the offensive end, I make plays."