The England Under 21 international has been signed on a season long loan deal.
Pennant was arrested last Sunday morning after a car he was said to have been driving was involved in an accident and he is due to answer charges at Aylesbury on Tuesday.
This put on hold an agreed loan deal with Arsenal last week pending the court case.
If all goes well for Pennant then he could go straight into the Blues squad for the game against Southampton on Wednesday night.