ERS will form part of Experian's Business Strategies division, allowing the combined businesses to provide a broader range of products and services to the public sector.
The services the combined entity can now offer will range from large-scale strategic government research projects to smaller, detailed local impact assessment studies.
Charles Burton, managing director of Experian's Business Strategies division, said: "We are delighted to welcome Economic Research Services to Business Strategies. ERS has built a formidable reputation in the public sector where it has been providing a range of specialised policy impact and evaluation services.
"Economic Research Services enjoys close synergies with our existing economics research business and we will gain from its unique and practical understanding of how government programmes and projects work at local level."
Launched in 1994 from its Newcastle base, ERS employs a team of specialised economic analysts, regeneration experts and researchers via a network of regional offices across the UK.