TBWA\London was tasked with creating the campaign, which will begin promoting the competition through radio and magazine ads rolling out next week.
The activity will direct consumers to the Muller website, where they will be asked to write 200 words detailing why they should be chosen to front the ads and upload pictures and videos of themselves.
Auditions, hosted by an as-yet unnamed celebrity, will determine the 100 winners, who could be any age between one and 100. Local advertising will focus on each of the winners, who will be revealed on poster sites at the end of January. The TV ad is expected to break in the first quarter of next year.
The campaign follows on from activity created by TBWA\London last year, under the strapline 'Lead a Muller life'. The work was intended to create a masterbrand associated with people enjoying life to the full.
In September, Muller launched two 30-second films on MySpace featuring a character called James, who travels the world in search of a snack as healthy and tasty as Muller Rice.
Muller is number-one in the UK yoghurt and yoghurt-drink sector, with 31.8% of the market in 2005, according to Mintel.
Footage from the auditions will be developed by Stream, TBWA\London's brand entertainment arm.