Manchester becomes the group's fourth office after London, New York and Stockholm.
Chelin, who officially began on 16 December, has joined from internal communications and employment engagement consultancy Scarlettabbott, where she served as head of client services. She brings years of internal comms skills and experience to the Manifest fold.
She has previously worked with Sainsbury's, EY, Asda, Co-op, Dixons Carphone, Vodafone, Rolls-Royce, EY, John Lewis, Morrisons, O2 and Santander, among other clients.
Manifest told PRWeek that expanding into Manchester was a natural evolution of its UK operation, but will also benefit the rest of the group globally. The agency already serves clients based in the north and the region is increasingly regarded as an important economic hub for British business. Several marcomms agency groups and media businesses have expanded their footprint in Manchester.
"Manchester is a natural home for radical creatives, with a wealth of talent and character that will enrich and embolden the Manifest culture as well as our creative output. It's an incredible city with so much to offer," Manifest Group founder and chief executive Alex Myers said.
"We are very excited to expand beyond the 'London bubble' and add a new dimension and dynamism to both our national work in the UK and our international group projects."
Chelin, who lives in York, said Manchester is a "fantastic fit" for Manifest's values.
"Historically, the creative, scientific and political industries that have borne Manchester talent have maintained a healthy disregard for the impossible and we're here to drink that culture in," she said. "It's very much not about London landing in Manchester to show the north how it's done. Quite the opposite, in fact.
"Because we're operating as a group, we'll service brands already part of the Manifest family, as well as inviting brands in the north to add us to their pitch lists so they can gain access to the creative and strategic expertise New York, Stockholm and London have to offer across all disciplines of the agency."
Manifest's expansion plans won't stop in Manchester. The group is looking to build a permanent presence on the West Coast of the US this year, and has its eye on an office in South Africa's Cape Town in the near future.
Manifest London recently won the ZipCar account and has received several industry accolades in the past year, including the International Agency of the Year at 2019 PRWeek Global Awards.