The England midfielder has not played this season since sustaining serious knee ligament damage in the semi-finals of the 2017-18 competition.
He has been added to the final 25-man group for the last-16 onwards, though, along with 17-year-old Ki-Jana Hoever and Ben Woodburn, who is on the B list.
Juventus have chosen to drop Juan Cuadrado, meanwhile, with the winger recovering from an operation on his left knee in December.
Barcelona have added B-team forward Moussa Wague to their squad, along with new signings Jeison Murillo and Kevin-Prince Boateng.
City have named Claudio Bravo on their list, with Eliaquim Mangala dropping out having not appeared for the club in the 2018-19 campaign.
All last-16 contenders were permitted to register a maximum of three new A-list players for the last 16 before the deadline of midnight CET last Saturday.
And the news regarding Oxlade-Chamberlain's inclusion will come as a boost for Liverpool and the player himself, with the Reds facing Bayern Munich in the last 16.
It is unclear exactly when the 25-year-old will be available to play again, although he posted on social media back in December to confirm that he was now able to begin running outdoors.
And Klopp revealed in January that he was hopeful he'd be able to play a part before the end of the season, hence his inclusion in the Champions League squad.
The German said: "He is in a very good way. That will still take a couple of... last time I put a bit of pressure on the medical department.
"But when I see him moving the ball and what he's doing already it looks really good, promising, close to a return.
"But after so long out – April, against Roma – he will be fine, he looks completely without any problems at the moment, no swelling any more, so he can really work on his fitness issues.
"It’s a surprise. He’s ahead of schedule. That’s always good news. We try not to push him too much but we don’t want to hold him back.
"If he makes further steps like he did in the last few weeks he can play Premier League football this season which is nice to know. I think we will see him this season."