Carter joins fellow freshmen Marvin Bagley III, Gary Trent Jr. and Trevon Duval in declaring with the intent to hire an agent. The Blue Devils, who signed the top three players in the Class of 2018, will also lose senior Grayson Allen.
"I want to thank Duke University, my coaches and teammates for helping me so much, not only on the court, but off it as well," Carter said in a statement released on Monday. "We're all brothers, we all have each other's backs. I'm really going to miss being around my friends, but I'm really going to cherish the moments we had together. I'm very excited and very happy to say I was part of something special here at Duke."
The 6-foot-10 Georgia native, who turned 19 on Monday, averaged 13.5 points and 9.1 rebounds while playing alongside Bagley on the Duke front line. Multiple NBA executives told ESPN that Carter is a likely lottery pick in the June draft.
"It was such an honor to coach Wendell," Duke coach Mike Krzyzewski said in a statement. "He and his family were a true joy to have in our program and they'll always be in our program. He had a sensational freshman year -- a double-double guy -- and he has so much more potential. He's going to keep getting better, because he's talented and he has the best attitude. He really represented himself, his family and Duke in a first-class manner, and whoever gets him is going to be very lucky."
Carter told The Undefeated that he has already interviewed five NBA agents and will be hiring one. He is uncertain if he will participate in the NBA pre-draft camp in Chicago.
"My emotions are kind of all over the place," Carter told ESPN's The Undefeated. "I'm excited to be chasing something that I wanted to chase my entire life. It was a pretty tough decision. I just wanted to make sure I made the right decision. "I'm just thankful that I had an opportunity to make that decision. I'm blessed to even have the opportunity to make a tough decision like that. I think I made the best one."
Carter's mother, Kylia, wanted her teenage son to return to Duke while his father, Wendell Sr., wanted him to enter the draft. Carter Jr. said that his parents helped him make his NBA decision by taking the emotion out and making a business decision.
When asked why the decision to go to the NBA was a difficult one for him, Carter Jr., said: "I fell in love with Duke in the short time I was there. Taking that next chapter in my life is difficult. There are going to be a lot of ups and downs coming up this next year. I just saw the pros and cons of both situations. It was difficult to say no to one thing and follow my heart with the other thing."
Information from The Undefeated's Marc J. Spears was used in this report.