Sidney Webb House, a 446-bed student hall of residence in Great Dover Street, has been sold by its Bahraini owners as part of a wider £271 million deal.
The seven-storey building provides accommodation for students of the London School of Economics.
Ahli United Bank of Bahrain bought the building in 2011 for £23 million.
Now it is part of a 2,100 bed student accommodation portfolio purchased by Unite UK Student Accommodation Fund for £271 million.
Unite Group plc has a 22 per cent stake in the fund.
"Following its recent capital raising, we are delighted that USAF has been able to complete the acquisition of one of the highest quality portfolios in the market," said Mark Allan, CEO of Unite Students.
"The portfolio is highly complementary to USAF's existing portfolio and we see real opportunities to drive additional value through the introduction of our brand and operating platform as well as specific asset management opportunities."