Manager Neil Warnock remains hopeful the club will be able to make a few more signings in January, yet loan deals seem the most likely outcome due to the current financial landscape.
We take a closer look at the signings Boro have already made under Warnock and how they have fared – scroll down and turn the page to see them all:
1. Grant Hall
After regaining his match fitness, Hall looked like he could be a shrewd signing for Boro after joining on a free transfer from QPR. The centre-back's injury record was always a concern though, and we haven't seen the 29-year-old since he hobbled off with a calf issue in September. Hall then suffered a thigh issue which will keep him sidelined for another few months. Photo: PA
2. Marcus Bettinelli
It may not look like the Fulham loanee has much to do most of the time, yet it's no coincidence Boro haven't faced as many shots since Bettinelli came in. The 28-year-old keeper can regularly be heard barking out instructions and keeping his team-mates in check. There are still question marks about Bettinelli’s shot stopping, though, and a couple of mistakes have proved costly. Photo: Getty Images
3. Sam Morsy
The former Wigan captain wasn't Warnock's first choice when looking at central midfielders in the summer. But after missing out on Joe Williams, who was also at Wigan, Boro brought in Morsy instead. The 29-year-old has been a big hit at the Riverside, providing extra bite and security in the engine room. He also has an eye for a pass when given time on the ball. Photo: Getty Images
4. Chuba Akpom
It all started so well for the striker who scored twice in his first two appearances for Boro. Akpom had to wait 13 games for his next goal, though, and was often played up front on his own as the side struggled to score. The 24-year-old does appear better suited to playing as part of a front two and has linked up well with Duncan Watmore in recent weeks. Photo: Getty Images