In the newly created role, Orr will oversee a team of 40 with a brief to evolve British Gas' "Look after your world" campaign by CHI & Partners and ensure that it is integrated across different channels.
British Gas previously split responsibility for advertising and direct marketing into two separate roles, both of which reported to the marketing director, Rick Vlemmiks.
Vlemmiks said: "I am delighted that we have found someone of Will's calibre and look forward to his contribution to the team."
British Gas' communications are handled by CHI & Partners, which has responsibility for advertising, and OgilvyOne, which works on direct marketing.
Its £50 million media account is currently up for review, with Mindshare and ZenithOptimedia battling it out for the business against the incumbent, Carat.
Orr, who joins on 28 June, said: "British Gas is making very rapid progress and has exciting plans for the future. Its ambition is to be one of the UK's strongest brands and my job is to help reach that goal."
The former WCRS chief executive left the agency in October last year after just 15 months in the role. He was previously the WCRS managing director. Orr, who had worked at WCRS until 2000, rejoined the agency in May 2005 from Mother.