Slater & Gordon, the Australian law firm which acquired Manchester's Pannone last year, has appointed TSK for the design and build of its new office at 58 Mosley Street.
The firm, which has acquired Russell Jones & Walker, Pannone and Fentons since its entry into the UK market in 2012, signed to take the whole 105,000 sq ft building.
Slater & Gordon is due to take occupation in early 2015, relocating from several sites including three interlinked buildings in Deansgate.
The building is owned by Bank of Ireland Asset Management, held in its New Ireland Pension Property Fund, and was formerly occupied by law firm Cobbetts, which collapsed into administration in early 2013.
Neil Kinsella, UK head of Slater & Gordon, said: "We want to be able to provide a first class office environment for our clients and staff in Manchester.
"Our people have been based around several different sites in the city for a number of months and everyone is excited that we now have a schedule for when we will all be working out of one Manchester office.
"58 Mosley Street provides us with an excellent central location to achieve that goal and provides us with capacity for future growth."
Part of the overall scheme currently being developed by TSK is for a community space on the ground floor to allow the firm to be more accessible to its clients.
Kinsella added: "The high street community space will be an area where members of the local community can just drop in, talk to a lawyer over a coffee and access legal information and resources in an approachable and relaxing environment."
Andrew Burns, TSK's joint managing director, said: "To be appointed by Slater & Gordon to design and build their prestigious Manchester office is testament not only to the quality of TSK's personnel but also our approach to projects.
Neil and his team have appreciated the benefits of using a single multi-disciplined organisation for the whole project rather than having to coordinate separate suppliers for the various elements.
''Our quality approach adds speed, delivers value and we look forward to working on this astonishing project in the heart of Manchester.''
OBI Property advised Slater & Gordon on the relocation.