The ratings agency moved Barrick from Baa3 to Baa2, going from 10th to ninth on its risk scale (both are considered a ‘moderate credit risk') of fixed-income obligations.
Moody's analyst Jamie Koutsoukis said the re-rating took into account this year's forecasts.
"The upgrade reflects Barrick's aggressive deleveraging with the expectation that debt will be reduced further, to about US$5 billion by the end of 2018, so that adjusted leverage will remain well below 2x even as production declines," he said.
Barrick paid off 19% of its debt in 2017, taking it down to $6.4 billion.
Moody's said gold prices would outweigh the fall in production.
"Barrick's production is expected to fall in 2018, with company guidance of 4.5-5 million attributable ounces in 2018 (5.3Moz in 2017), however we expect leverage will remain well below 2x based on expected strong EBITDA and free cash flow generation and Barrick's commitment to reduce adjusted debt further," the agency said.
"We expect Barrick will stabilise production through various low-risk brownfield projects and it may eventually pursue greenfield projects, but in a much more prudent manner than in the past, sharing risk with partners, and prioritising low leverage over growth and size."
Analysts have questioned Barrick's production profile past 2020 but the sticking point this year will be costs, RBC's Stephen Walker said last month.
"While the [December quarter] results, 2018 and long-term production guidance were solid, the AISC outlook is now well above previous guidance," he said.
The company said last week that its AISC was expected to go from $750 per ounce in 2017 to $765-815/oz in 2018 and a much wider range of $750-$875/oz in 2019-2022.
Barrick's share price was up 1.5% following the Moody's announcement.