The former Crystal Palace player sealed his move from Bristol Rovers after initially agreeing a deal with the East London outfit in June.
The 24-year-old has been able to prove to O's boss Martin Ling (pictured) that he had recovered from a knee operation back in February.
Ling was pleased that Carlisle was fit enough to be ready for the new season that begins next month.
"Over the ten days that he has been with us now, Wayne has proven that he is fully fit and ready to go," Ling told the club's official website.
"He's done everything we've asked him to - from a five-mile race to an 11-a-side game and he's not suffered any repercussions.
"We didn't anticipate there being any problems, but this was the best way to prove it both for ourselves and for him and I'm pleased it's all worked out as he will give us a good option in midfield and attack."
