The deal comes after chief executive David Atkins put the offices up for sale in February to focus on retail property in the UK and France.
The FTSE 100 firm’s retail assets account for 90 per cent of its portfolio and include London’s Brent Cross and the Bullring in Birmingham.
Under the deal, Brookfield will pay Hammerson £329m for 99 Bishopsgate, Principal Place and two smaller assets by 30 September.
The sale of 125 Old Broad Street – the former Stock Exchange – and Leadenhall Court will be completed in June next year for £189m.
Hammerson said it will reinvest the proceeds in retail developments and buying up prime regional shopping centres, retail parks and premium designer outlets.
Martin Jepson, Brookfield’s senior vice president for investment, who joined from Hammerson last year, said the deal gave the firm “a platform for our portfolio in the UK”.
He said the building of Principal Place would kick-off once they had found a pre-let tenant.