Ellis has been named among the replacements for Leicester's Guinness Premiership clash against Madejski Stadium hosts London Irish on Sunday.
His full recovery comes less than three weeks after he was injured during Tigers' European Cup victory over the Ospreys, an incident which saw Ospreys lock Ian Evans cited and banned for eight weeks.
And it will provide a huge lift for England head coach Andy Robinson, with the world champions' Six Nations opener against Wales barely a month away.
"Harry is 100% fit, and he has done really well to get back as quickly as he has," said Tigers head coach Pat Howard.
"At the start of the week, he wasn't really in my plans because I thought he would need another week, but he has worked exceptionally hard and I think it is a testament to his work ethic."