The agency will take over from two-year incumbent Ceres on the account, which is understood to be worth £100,000 in fees.
Nexus will work from now until the end of next February, when National Chip Week is scheduled to take place.
Nexus director Jon Meakin explained that the Potato Council wanted to 'freshen up' the week.
'We're prepared for it,' said Meakin on the potential for media attacks concerning health issues. 'There are plenty of people prepared to have a pop at potatoes, especially chips.'
Nexus has also been hired by the Potato Council to handle a campaign to promote the healthiness of potatoes. The health brief is understood to be worth £70,000 over eight months, starting next summer.
The win follows Nexus' appointment by McCain Foods earlier this month.