AEG Live and co-owner German ticketing vendor CTS Eventim are renovating the building as part of a multi-million pound scheme.
The venue is set to open again on 7 September with a performance by US pop starlet Selena Gomez.
The agency is managing PR for the revamp as well as providing strategic and creative counsel.
The brief includes repositioning the Hammersmith Apollo to highlight its stylish environment and world-class facilities for a live entertainment audience. W will activate a programme of engagement across print, broadcast and online media to deliver a bespoke campaign that will promote the venue and amplify the work that has gone into reviving its Art Deco styling.
W founder Warren Johnson said: 'It's a London icon and we're looking to remind people of that as we bring it back to its original 1932 art deco glory. This won't just be a London story - we're looking to spread word of the Apollo globally as a piece of London's history.'