Blues boss Steve Bruce is delighted to land the 20-year-old's services until January 2008, although there is an option to extend the deal to include the whole of the season.
And Bruce believes Djourou has a long Arsenal future ahead of him.
"I honestly think that Djourou can be an Arsenal defender for 10 years," stated Bruce. "I am delighted Arsene Wenger has allowed Johan to join us.
"He has got strength, pace, great ability on the ball, is a very good footballer and is comfortable at the back and in midfield."
The Swiss international is eligible to make his debut against Chelsea in this weekend's season opener and Wenger will be keeping close tabs on his development at St Andrews.
Djourou made 21 Premier League appearances last season as injuries struck down new signing William Gallas, Philippe Senderos and Emmanuel Eboue.
Wth,the afraican defenders going for african nations cup..then we'll left with willy and senderos only for our CB! 
