The 38-year old had his contract with the Trotters terminated by mutual consent so that he could find a club which was nearer to his London based home.
Royals boss Steve Coppell was looking for extra additions to help his sides promotion push and the capture of the former Newcastle United and Tottenham Hotspur player could prove to be an astute signing.
Ferdinand had also been a target of former club Queens Park Rangers and Southampton before the promotion chasers Reading took him to the Madjeski Stadium.
Bolton Mad would like to wish Les the best of luck in Berkshire.