The fast-food giant is currently battling the expansion of Subway, a US sandwich chain, which aims to overtake McDonald's in terms of UK outlet numbers within four years.
The activity, which has been created by Leo Burnett, with media through OMD, will run across TV, outdoor, print, online and radio. It will include McDonald's biggest investment to date in digital marketing.
The campaign, which will promote McDonald's as the destination for a freshly prepared sandwich, will feature 60-second TV ads for the first time in three years to ensure maximum coverage.
The ads, which break today, will run simultaneously on ITV, Channel 4, Five and some satellite stations.
Online and radio activity will be timed to run in the key lunchtime period, between 10.30am and 2.30pm.
The campaign will focus on the quality of the sandwiches. This follows the line taken by McDonald's recent 'Quality' campaign, which was intended to encourage consumers to reappraise the ingredients in its products.
The toasted deli sandwich range is the latest menu innovation to be implemented by McDonald's following consumer concerns about rising obesity levels in the UK.
The chain recently cut several products to make space for the sandwiches, which are being rolled out nationwide.
Laurie Morgan, McDonald's vice-president and chief marketing officer, is heading the launch.
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