The company issued a voluntary redemption note of $160 million for the remaining balance of 9.75% senior secured notes due in 2022.
The notes will repaid from operating cashflow on June 28.
"The repayment of the high-cost notes now leaves all of Fortescue's remaining debt structured on investment-grade terms and conditions, providing a low-cost, flexible capital structure to support our ongoing operations and future growth," FMG chief financial officer Ian Wells said.
Net debt at March 31 stood at $3.3 billion, while gross debt was at $5.6 billion, but was set to reduce to $4.1 billion after repayments last month.
FMG is due to make a final investment decision on the $1-1.5 billion Firetail replacement project, Eliwana, by the end of next month.
Shares in FMG dropped by 1.3% to A$4.53 today, the lowest level so far this month.
