Head of communications William Miller, who joined the organisation last month, has hired media and entertainment specialist PagetBaker PR after a two-week, three-way pitch process against undisclosed agencies.
The gallery is due to open in April and will display works from artists including Tracey Emin and Damien Hirst.
Miller handles all marketing, promotional and PR work for the gallery and reports to gallery curator and collector Charles Saatchi, who made his fortune in advertising.
'An enormous amount of people have heard or read about art such as Tracey Emin's bed, but they have never really had the opportunity to see it,' said Miller.
A PR campaign undertaken by PagetBaker will attempt to 'reach a much broader field of people' than would normally attend art exhibitions, according to Miller.
'A much wider British audience is interested in contemporary art in a way that previous generations may not have been,' he added.
Saatchi secured the exhibition space in County Hall last month.
Miller was new media director at Conde Nast for around 12 months until June 2001. After that he formed production company Pabulum Media, which he continues to run as CEO.