AXA Real Estate has secured the first letting at 55 Portland Street in Manchester city centre.
Language school Alliance Francaise has signed a 10 year lease on the third floor totalling 5,283 sq ft for an undisclosed rent.
The former CIS Tower was previously occupied by Co–operative Insurance Society, now known as Co–operative Insurance.
The 11-storey building has undergone a programme of refurbishment over the last 12 months to provide 70,000 sq ft of grade A office accommodation and new reception area.
Rob Peill, leasing agent at Matthews & Goodman, who acted on behalf of AXA Real Estate, said: "The quality of the refurbishment and competitively priced rental levels have generated strong early interest in the building from a diverse range of occupiers."
Peill added that another floor is also under offer and expected to be completed in two weeks.
Alliance Francaise is currently based in the fourth floor of Churchgate House at 56 Oxford Street in Manchester and will be moving to its new office in August.
The French language school also has offices in Paris, London and Glasgow. Drivers Jonas Deloitte acted on behalf of Alliance Francaise in the deal.
Adam Robson, assistant director at Drivers Jonas Deloitte, said: "The move to Portland Street will allow the company to continue its work from a more central location in the heart of Manchester's vibrant city centre."
WHR Property Consultants are joint agents on 55 Portland Street.