The former Arsenal player has signed an initial six-month contract with the midlands side at the age of 37.
Pires will go straight into contention for Sunday's game at Blackburn after training with the Gunners for the past two months.
He said: "I like football. It's my passion. If I have the mentality I will go to six months or why not more?
"Can I play until 40? I think so, yes.
"Every day, every morning, it is difficult. If you are younger, it is easy. But, if you have the mentality, it is not a problem."