It is understood the public affairs account, which FleishmanHillard Fishburn held since 2013, was taken over by Headland in January following discussions with PepsiCo.
Headland will now offer PepsiCo an integrated "one agency" approach, having won the long-standing corporate comms account from Freuds last year.
The combined account is led by Headland partner Simon Burton, who joined the agency in September 2015 from a senior in-house role at Tesco.
PepsiCo's brands include Pepsi, Tropicana, Walkers and Doritos.
It is understood Headland will work across a number of PepsiCo brands, as well as handling the company's public health agenda, which includes lobbying against the proposed "sugar tax". The proposed tax will see the UK government add two sepearte levies of 18p and 24p per litre to sugary soft drinks in April 2018.
PRWeek contacted FleishmanHillard Fishburn for comment, but the agency was yet to respond at the time of publication.
Headland declined to comment.