By David Winning

SYDNEY--Origin Energy Ltd. reported a sharp fall in annual profit as it absorbed a large writedown of its Australia Pacific LNG project and felt the sting of lower wholesale energy prices and reduced revenue from liquefied natural gas sales.

Origin reported a net profit of 83 million Australian dollars (US$59.6 million) in the 12 months through June, compared with a profit of A$1.21 billion a year earlier.

The result included a large writedown of assets, which Origin had signaled in mid-July as it adjusted to a weaker outlook for commodity prices and the ongoing economic impact of the coronavirus pandemic. An impairment of its share of the Australia Pacific LNG project was driven by lower oil-price assumptions.

"With the pandemic causing a reduction in electricity and gas demand, Origin was able to utilize the flexibility of our generation fleet and wholesale gas portfolio, as well as portfolio flexibility at Australia Pacific LNG, to adapt to market conditions and mitigate impacts on the business," said Chief Executive Frank Calabria.

Underlying earnings before interest, tax, depreciation and amortization were 2.8% lower at A$3.14 billion. Underlying Ebitda from its Energy Markets business totaled A$1.46 billion, in line with its earlier forecast for between A$1.4 billion and A$1.5 billion.

Directors of the company declared a final dividend of 10 cents a share, bringing the full-year payout to 25 cents.

Write to David Winning at david.winning@wsj.com