The contract will run for four years with a possible two year extension.
London Overground was set up in 2007 and runs routes across London on several lines including from Richmond to Stratford and Watford Junction to Euston. It is managed by Transport for London and by 2010 it should also include the East London Railway.
It is introducing new rolling stock over the next few months and KBH will initially install 1,000 landscape cards, rising to 3,000 with the East London Line reopening
KBH launched in 1998 and specialises in rail transport. It now has contracts for 50,000 panels on its London commuter routes.