Chelsea return for club great Drogba
Ivory Coast's forward Didier Drogba arrives for a training session at the Toyota Stadium in Frisco, Texas, on June 3, 2014 - by Jewel Samad
"He's coming because he's one of the best strikers in Europe," said Chelsea manager Jose Mourinho on the club website.
"I know his personality very well and I know if he comes back he's not protected by history or what he's done for this club previously. He is coming with the mentality to make more history."
Drogba, 36, was a free agent after leaving Galatasaray at the end of last season.
The Ivory Coast star scored 157 goals for Chelsea over an eight-year period and left the club in 2012 shortly after scoring the winning penalty against Bayern Munich in the Champions League final.