Benmore Group has let 8,000 sq ft to the language school; taking the refurbished property in Manchester city centre to full occupation.
A2Z English has agreed on a five year lease at 75 Mosley Street for an undisclosed sum.
In the past twelve months, Benmore has completed lettings with companies including Remploy and Scanlans LLP.
Nick Nelson, surveyor in the office agency team at CBRE North West, joint agent on the building, said: "Since our instruction a year ago alongside P3 Property Consultants, we have successfully completed three new lettings totalling 16,500 sq ft to achieve a fully let building for our client, the Benmore Group.
"This is evidence that there remains healthy demand for competitively priced, good quality refurbished office accommodation in buildings that offer prime location and flexible lease terms."