The 20-year-old, who came through the youth system at Chelsea, made three Premier League appearances for the Blues last season.
New Hull head coach Leonid Slutsky recently revealed that he could look to use his close relationship with Chelsea owner Roman Abramovich to secure new signings this summer, and Aina has now made the switch to the KCOM Stadium.
"I'm very excited to be here and it is the start of a new chapter in my career. It's my first loan move away from Chelsea and I just want to hit the ground running. I'm looking forward to getting to know all of my new teammates during the training camp in Portugal," Aina told Hull's official website.
Aina has represented England at Under-16, Under-17, Under-18, Under-19 and Under-20 level, but the versatile defender recently committed his international future to Nigeria.