The London-based practice saw off competition from a shortlist including Jestico & Whiles Associates, Walter Menteth Architects, PCKO Architects and Anne Thorne Architects.
The designs were judged by representatives from Ujima as well as Teresa Borsuk, principal of Pollard Thomas Edwards Architects.
According to a statement, the panel felt that A-EM had 'submitted an exciting, innovative scheme that would help Ujima create an architectural sense of place, with enhanced use of public realm.'
Ujima development consultant Malcolm Gardner said: 'I am really excited by the winning scheme, which I look forward to developing with the A-EM team and the local authority. The retention of the scheme's key elements will be critical to its successful implementation as the scheme progresses.'