The WPP Group agency beat out competition for the brief from Publicis agency ZenithOptimedia and media independent Booth Lockett Makin to take the business.
The pitch was handled through the COI because Jobcentre Plus is part of the Department of Work and Pensions.
The COI said that the aim of the campaign would be to promote Jobcentre Plus as a professional and modern service for employers and people searching for work.
For those seeking work, this includes the ability to search for jobs online and over the phone, plus advice on training and benefits.
Mediaedge:cia will also be tasked with promoting the government department as a one-stop-shop that can help employers fill vacancies quickly and successfully.
Tom George, managing director of Mediaedge:cia, said: "Jobcentre Plus is an incredibly thought-provoking and interesting client, and we are looking forward to working with them. It's great to win the business in the face of such stiff competition."
Mediaedge:cia was reappointed to the COI's communication's planning roster in February this year along with six other media agencies. As well as the reappointments, seven new agencies were added to the roster.
The win follows that of the £2m UK account for online job portal Monster.com, the agency was also handed the global brief.
Mediaedge:cia and COI confirmed that the agency had been awarded the Jobcentre Plus brief.
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