BP has paid $1.3bn (£1.1bn) for the petrol station business of Woolworths, the Australian supermarket chain.
The deal adds 527 service stations and 16 sites under construction to the 350 outlets BP already owns in the country.
The two firms will trial a convenience store business at 200 stations as part of the agreement.
The move follows the success of BP’s Simply Food forecourt chain in the UK, which it runs with Marks & Spencer.
There are 248 Simply Food at BP stations in the UK, while the oil giant plans to open 50 more in 2017.
Tufan Erginbilgic, chief executive of BP Downstream, said: “Globally we have developed a winning retail formula where we partner with strong local brands, like Marks & Spencer in the UK, to provide our customers with a convenience retail offer that meets the needs of their busy lifestyles.”
BP said the deal, which was first proposed in September, would be completed by January 2018, subject to regulatory approval.
The UK firm is seeking new ways to drive growth after being hit by the slump in global oil prices since 2014.
In the three months to September, it reported profits of $933m (£763m) on an underlying replacement cost basis, down from $1.8bn a year earlier.
The firm also said in December it would invest almost $1bn to explore the Tortue gas field off the coasts of Mauritania and Senegal.
Shares in BP have risen more than 40% this year and were 1.2% higher at 509.1p in afternoon trading in London.