AP, which bills itself as the 'world's oldest and largest newsgathering organisation', appointed the agency after a competitive pitch.
Speed will remain on board for two to three years, leading issues-led, thought leadership and corporate programmes to help build the AP brand and affirm its credibility as a news organisation.
The account will be led by director Scott McLean, who said: 'Journalism is under assault from reduced production budgets and rumour-filled social media sites, yet professional journalism is more important than ever. AP needs to continue to distance itself from the often inaccurate Twitter feeds and position itself as the credible news source.'
McLean added: 'AP has stood its ground and allowed quality journalism to find its place in the digital world.'
A four-person Speed team will base itself within the London AP news centre, reporting to marketing director, EMEA & Asia, Julia Howe.
Howe said of the appointment: 'Speed's role will be to help AP tell its own story - a story of global exclusives, award-winning journalism and resolute trust.'
AP is one of the three major international news agencies, alongside Reuters and AFP, and delivers news to thousands of daily newspaper, radio, television and online customers.
In a recent interview with PRWeek, Channel 4 News presenter Krishnan Guru-Murthy noted some news organisations were cancelling subscriptions to newswires in favour of using Twitter.
Speed plans to position AP as an essential tool rather than an add-on for news organisations.
'Gone are the days when newsrooms could just sign up to every news wire going - they need to justify their cost,' said McLean.