Ogunneye moves to the Welsh club on a season-long loan.
The London-born defender is reunited at Newport with Dave Hughes, who left his role as United’s Under-21s assistant manager at the end of last season.
“Once I knew Newport were interested and Dave Hughes was there then it was an easy decision for me,’’ Ogunneye told Newport's website. “I worked closely with him at Manchester United for two years and he is a great coach. He taught me a lot, and I have the utmost respect for him.
“It was an important decision for me because it is my first loan in senior football. I felt the time was right for me to take the step and I’m really looking forward to the challenge.
“I met and trained with the squad on Monday, and they have been great with me. They are all willing to work hard, set standards, and I want to play my part.
“I want to play as many games as I can and help the team be successful.’’