The steelmaker on Monday reported a 64 per cent drop in net profit to $1.01 billion for the year ending June 30.
Chairman John Bevan said the comprehensive reline and upgrade of a blast furnace at the NSW south coast smelter, when commissioned in mid to late 2026, would allow the company to maintain steel production as it decarbonises its operations.
"It secures our immediate future while enabling a transition to lower emissions steelmaking as soon as it is commercially feasible," Mr Bevan said.
"In this sense the reline project is our bridge to the future and critical to maintaining the sovereign capability of flat steelmaking in Australia."
BlueScope reported underlying earnings before interest and tax of $1.6 billion, in line with guidance.
Lower global steel prices smashed a $2.1 billion dent in earnings, but was partially offset by lower material costs and a ramp up in production volumes at its US steel mill North Star.
Domestic Colorbond steel sales were the highest on record, driven by marketing initiatives and strong demand.
BlueScope has also started construction on a $415 million metal coating line in western Sydney to boost production of value-added products such as Colorbond.
The 240 kilotonne per annum plant is due to be completed by the end of 2025.
After earnings for the second half came in at $757 million, the company expects a similar result for the first half of financial year 2024.
BlueScope announced a full-year dividend of 25c per share fully franked
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