Seal won the project after a six-way pitch against three local agencies and two London-based agencies.
Marketing Birmingham is a public-private partnership receiving financial support from Birmingham City Council and some 350 member companies and private investors.
Katie Morris, Seal Communications chief executive, said: "As a long-established Birmingham- based agency we have been part of the city's renaissance in recent years, having witnessed first hand the amazing transformation that has taken place both culturally and through investment in the retail and leisure offering.
"Our work for Marketing Birmingham will build on our broad experience of working on destination marketing campaigns both in the UK and for tourism bodies internationally."
The campaign will also coincide with the redevelopment of Birmingham's official tourism website by digital agency Tak!
Dave Hodgson, marketing director at Marketing Birmingham said: "Birmingham is a great city with a lot to offer and one of the most difficult parts of marketing it, is choosing which bits to single out and promote.
"We're thrilled to have appointed Seal as a local agency that really demonstrated its ability to look at the bigger picture. The ideas that Seal presented fitted the brief perfectly and I'm looking forward to working with them to bring the campaign to life."