The site at Crewe Toll, which is home to advanced engineering company Leonardo, was sold by owners Brockton Capital in an off-market transaction.
It was bought on behalf of an unnamed investor by Knight Frank Investment Management.
The site includes the Leonardo innovation hub, which covers 439,000 sq ft of office, lab and industrial space.
The aerospace, defence and security company, which employs about 1,800 staff in Edinburgh, recently signed a new 15-year lease at the hub.
Originally built in the 1940s, the base produces cutting-edge technology such as lasers for the US Army's Apache helicopter and the Captor radar for the Typhoon.
The acquisition is the second major commercial property deal Edinburgh has seen in recent weeks. Last month a German pension fund bought a major office and leisure development in the city centre for £120m.
The buildings at 4-8 St Andrew Square include offices for pensions giant Standard Life Aberdeen (SLA), a number of restaurants and a large TK Maxx store. The site had been developed by Aberdeen Standard Investments (ASI) in conjunction with Peveril Securities...