The quarter's adjusted net loss was 27 cents a share, bettering analysts' expectation of a 68-cent loss. Revenue of $2.56 billion came in ahead of the Zacks consensus estimate of $2.54 billion.
"We finished 2020 strong and are optimistic about the opportunity to deliver incremental value for our stakeholders in 2021," Chief Executive David Burritt said in a statement.
"Our performance continues to strengthen as we enter 2021 and we are bullish that the market will continue to be fueled by robust demand, low inventories, and supportive raw material prices."
At last check U.S. Steel shares jumped 6.3% to $19.90.
The company said it benefitted from cost-management initiatives as well as higher prices in the quarter.
Its European operations reported profit of $36 million, swinging from a loss of $30 million in the year-earlier period.
In September, going into the fourth quarter, U.S. Steel said that improving market conditions in June and July accelerated through August and September, making the company bullish on its third-quarter results.
"Strengthening steel fundamentals and our ability to respond quickly to increasing customer demand are expected to result in significantly improved adjusted earnings before interest, taxes, depreciation and amortization in the third quarter," Burritt said at the time.