The institute is opening its doors to agencies with specific movie expertise to pitch for the next three years of the festival.
Taking place in the second half of October, the festival last year featured guests including George Clooney, Madonna and Ralph Fiennes walking the red carpet.
The festival is the UK's largest public film event, screening more than 300 features, documentaries and shorts from almost 50 countries.
BFI head of press and PR Judy Wells told PRWeek: 'The winning agency will need to employ specific skills relating to film-festival public relations as well as demonstrate an understanding of the film landscape.'
The BFI, which promotes and preserves the UK's film industry and heritage, has told PRWeek that it hopes pitching will take place at the beginning of May, with an agency in place by the end of that month.
The contract up for grabs spans the festival from this year's outing to the event in 2014.
The incumbent agency, Premier PR, will be invited to repitch for the business. The agency has held the brief since 2000, having successfully repitched in 2005 and 2011.
A separate account for the opening and closing galas has been held by Freud Communications for six years and ends in April 2013.
The appointed agency's remit will cover the festival's overall PR strategy, media relations, press accreditation and screenings, red carpet media management and media partnerships.
The agency will work closely with Clare Stewart, BFI head of exhibitions, and report to Wells.
Stewart said: 'The BFI London Film Festival is internationally recognised and admired, and an effective press campaign is going to be vital in getting us noticed and communicating the rich breadth of the programme.'