The former Arsenal and Liverpool midfielder has penned a deal to the end of the season. Oxlade-Chamberlain joins Celtic as a free agent after leaving Besiktas in the summer.
The 32-year-old told Celtic TV: "It's been a busy few days. Speaking with the manager, it just felt like the perfect fit for me, and I feel like I can come in and help the lads.
"The manager, and Shaun Maloney as well, told me about the expectations on the club and what it means to play here, what our targets are and that he’s going to push me.
"That’s all the stuff I identify with and that’s the environment I’ve always been in and been lucky enough to be in."
Oxlade-Chamberlain added, "It’s exactly what I need.
"I need another challenge and lucky enough at a massive club like this. And they can help me get back to where I need to get to and, more importantly, I need to help the team achieve the goals we want to do."