The 30-year-old Girls Aloud singer, who is set to release her debut solo album next year, is fronting the nationwide competition with Yates, which aims to find positive photography of Britain taken by members of the British public.
Speaking about her role, which sees the star posing in a red and white dress behind the new Pentax K-30 DSLR camera, Harding said: "I'm really proud of my British roots, so to be an ambassador for Pentax and to fly the flag for the Meet Britain campaign is really exciting.
"There are so many world-class events taking place in the UK this summer, from music festivals to major sporting occasions - there is something for everyone to capture on camera."
The catergories for the competition include summer holidays, friends and family, celebrations, great British culture and the great British outdoors. Harding and Yates, using the new Pentax K-30 DSLR, will submit their own set of images, demonstrating people and places which make Britain so special.
Find out more about the Pentax campaign here.