Lucky Generals won the account after a competitive pitch. Popchips did not use an intermediary.
Ruth Elliott, the European marketing manager at Popchips, said: "Lucky Generals has really impressed us with their bold thinking and its modern creative approach.
"We have big plans and think they're the perfect partner to take Popchips to the next level in the UK."
Popchips launched in the UK in 2012 and put £1 million behind its first TV advertising campaign in January. Mindshare is the brand's media agency.
The work, which was created by Dandelion in the US and adapted for the UK by Aesop, showed a magician and his assistant arguing about how they would advertise the snack’s low-fat credentials.
An earlier print campaign from the brand, which was created in 2012 by the Californian agency Zambezi featured the singer Katy Perry, who was also a minority investor in the product.
Helen Calcraft, a co-founder of Lucky Generals, said: "There is a huge opportunity for Popchips in the UK and we look forward to creating a campaign that matches the team's ambition."