The 25-year-old missed the Blues' end-of-season run in and Wales' summer tour of Australia and has also sat out the first two games of the new PRO12 campaign.
But he has now finally been named on the replacements' bench for Saturday's South Wales derby against the Dragons, much to the delight of Blues boss Phil Davies.
"He's had a serious operation but has worked exceptionally hard," said Davies.
"He's got good body hardness, good timing and is ready to play. I'm excited from what I've seen of him on the training field."
Roberts is eager to get back involved in what could be a huge season for club, country and the Lions, especially as he admits his spell on the sidelines has been a frustrating one.
"It's been a pretty long time since the operation at the start of April. But I've done what I needed to do and got back where I needed to be," said Roberts.
"It's been quite tough. I was massively gutted to miss the Heineken Cup quarter-final and Wales' summer tour of Australia.
"It was hugely frustrating. Watching it on telly isn't quite the same, but it does make you hungry to come back. I've worked hard with the trainers and the conditioning staff and I'm raring to go again.
"There's a hugely-challenging season ahead and it's great to be back involved. It's been a long time away from the pitch and I can't wait to get back playing."
Rather than moan about his misfortune over recent months, Roberts believes the lay off could ultimately be a blessing in disguise as he looks to regain the form that saw him play such a vital role for the Lions last time out.
"When you have a long-term injury, you have to try and look at it positively. You can't afford to dwell on it or be negative about it. Rugby's a sport where injuries are going to happen. You have to put a positive spin on things and look on it in a good light.
"I've had three or four years of flat-out club and international rugby and that has been quite challenging. To have time away from the game, mentally and physically, is important.
"I've got the body back right and I've taken a mental break more than anything and come back refreshed."