The debt, underwritten by Credit Suisse and JP Morgan, gives the Perth-based company until November 2015 to make its first repayment.
"Fortescue has moved quickly to ensure its capital structure can withstand prolonged market volatility," chief executive Nev Power said in a statement.
Earlier this month, Fortescue announced it was slamming the brakes on plans to triple its iron ore capacity, cutting $1.6bn in planned capital spending this year, axing hundreds of jobs and selling a power station to preserve cash.
Iron ore prices have plummeted in recent weeks as demand in China shrinks. Australia is the world’s biggest exporter of iron ore.