The 20-year-old was being linked with a return to Celtic for weeks now and all parties will be delighted to have sealed the move.
Roberts had an outstanding 18-month loan spell at Celtic and Brendan Rodgers was keen to bring him back to the club this summer. Roberts joined the Hoops back in 2016 from City.
Although other clubs were interested in the attacking midfielder, he wanted to join the Scottish champions.
The transfer has been confirmed on Celtic’s official website and the player will wear the number 7 shirt worn in the past by Celtic legends such as Jimmy Johnstone and Henrik Larsson.