In January the agency hired Alex Stoneham as digital communications director and Joe Woollen as head of digital media.
Haslam will work alongside both and will report to the agency's joint creative directors Nick Platt and Barney Cockerell.
Marco Scognamiglio, chief executive of WWAV Rapp Collins Group, said: "We have now placed digital at the heart of planning across all clients and can offer the best digital media solutions executed with the highest standards in creativity."
At OgilvyOne, Haslam was associate creative director, producing digital, direct and above the line work for clients including First Great Western, IBM, American Express and HBOS.
Prior to working at OgilvyOne, Haslam was digital creative director at Redwood New Media, where he worked across a range of accounts including Boots, Eurostar and Volvo.