It has been reported that the Championship club have finalised a loan deal with Premier League giants City over the signing of the winger on a loan deal.
The former Celtic loanee has already passed a medical at Boro, who will make an announcement imminently.
Roberts has been on the books of City since the summer of 2015 when he joined from Fulham.
The 23-year-old winger has failed to break into the Citizens first team and has been out on loan in recent years.
The former England Under-20 international has been on loan at Celtic, Girona, Norwich City and Middlesbrough in recent years.
During his loan spell at the Riverside Stadium during the second half of last season, Roberts made eight starts and two substitute appearances in the Championship, scoring one goal and providing two assists in the process.