The campaign runs from today (20 October) until Sunday and encourages people to take pictures of the faces, places, moments and rituals that represent British life.
Entries can be submitted across 14 categories and Rankin will collate the 500 most striking images into a coffee table book sold via Photobox, with the brand hoping to raise £250,000 through its sales.
Based on previous competition participation rates among the Photobox community of one in 18 individuals, it hopes that 250,000 people will take part.
As part of the campaign, Rankin has also created a photography masterclass video (below) designed to help budding photographers take the perfect picture using nothing more than a smartphone.
He said: "My general rule of thumb is if you didn't make it, don't post it, which is why I never post photos of food. Unless you're the chef, no burgers or avocados on toast. Unless you're the crane driver, no cranes. The point is to think about what makes your day unique; things you see, things you find funny."
A number of photojournalists, including David Montgomery and Paul Postle, will also be taking part in This is Britain. Cult Brand is providing PR and strategic support for the campaign.