The duo paid $20.4 million for three adjoining development sites, giving it some 4652 square metres or more than an acre of land to develop a major project.
The purchase includes a 2464 sq m development site at 95-101 Bay Street, sold by developer Central Equity.
An adjoining group of buildings, on a total of about 2051 sq m and with a street frontage of 87-93 Bay Street, was also sold. Both sites have rear access to Nott Street.
Valad Property Group will amend an office permit for a nine-level building obtained by Central Equity before it listed the property for sale.
Valad will also develop a residential building over the three sites.
Sources say the project could have an end value of more than $150 million, and is expected to include ground-floor retail.
Central Equity put its property on the market in March to focus on bigger projects.
Jones Lang LaSalle director Dominic Gibson and Steve Messina negotiated the sales.
"Demand for inner-city residential sites is still quite resilient, given the underlying demand for housing and investors confidence in the strong rental market at present," Mr Gibson said.
Mr Messina said quality development sites are selling strongly despite less players.