Both are $500 million, but one is a five-year bond with a coupon of 5.125% and the other is a 10-year bond with a coupon of 6.125%.
Gold Fields said the final combined book for the bond issues was more than $3 billion.
The company said it would repay what remained of its $1.29 billion existing credit line, and refinance or repurchase other debt.
"One of Gold Fields' financial targets in its 2019 balanced scorecard is to improve the liquidity and profile of the group's debt," it said.
"This entails both reducing net debt and extending the maturity of the debt profile. The bond issue extends and spreads out the maturity of the debt profile."
Gold Fields owns the Agnew/Lawlers, Granny Smith and St Ives gold mines in Western Australia, as well as 50% of the Gruyere project, which is due to pour first gold this quarter.