The new look packaging will roll out to other major supermarkets during the first two weeks of October. The redesign extends to Jordans' Country Crisp cereal and Frusli bars, which will switch to the new look later in the year.
The Jordan family have been millers for over 150 years and began making natural wholegrain muesli in the 1970s.
The latest makeover has been designed to highlight the "nature-friendly" farming scheme that the company has been pioneering since the mid-1980s.
A new strapline has been devised to accompany the relaunch: "You can taste we care".
Shaun Bowen, creative director at Pearlfisher, said: "We have created a natural world of Jordans, starting at the mill and continuing around the pack with illustrations that reflect the personality of each flavour variant.
"The bold colours are crammed full of taste and are offset by the white sky which allows the Jordans logo more prominence than ever before."
Carol Welch, marketing and innovation director at Jordans, said: "The new packs look fantastic and successfully bring the world of Jordans to life in a compelling and engaging way.
"Pearlfisher's designs have been central to the development of a truly integrated marketing campaign for the brand, acting as the core creative stimulus for our advertising and website design as well."