Royal London Asset Management has let 10,000 sq ft at Alaska House within Atlantic Park in Sefton to Capita Symonds.
Property consultancy Capita has agreed to take an office in the third floor of the building for an undisclosed sum.
Mark Worthington, director at CB Richard Ellis in Liverpool, said: "We are absolutely delighted to have finally attracted Capita to Atlantic Park. The letting is a major boost for the development which is of great importance to the south Sefton area and represents the largest out of town transaction in Liverpool this year."
GVA Grimley is joint agent on Atlantic Park.