Muse Developments and joint venture partner United Utilities reported the letting of the fourth and final office building at the Clearwater phase of their Lingley Mere Business Park in Warrington.
Global engineering giant MWH has taken the last remaining building, comprising 9,044 sq ft.
The JV is progressing plans for an 18,500 sq ft building to follow the 54,600 sq ft first phase.
Phil Mayall, senior development surveyor at Muse Developments, said: "The successful completion of the Clearwater phase combined with the new UU Shared Service Centre and Regional Fire Control Centre buildings is testament to the superb business environment provided by Lingley Mere."
Lingley Mere currently provides 380,000 sq ft of offices within 100 acres of parkland and has permission for 1m sq ft in total.