The earnings per share topped analysts’ expectations, although the revenue was disappointing.
Fourth-quarter net income was $383 million, or 44 cents per share, compared with $261 million, or 30 cents per share, a year earlier.
Revenue was flat with a year ago at $3.70 billion.
Analysts surveyed by FactSet expected the company to earn 39 cents per share on revenue of $4.56 billion.
While quarterly revenue rose $7 million, the company slashed operating expenses by $218 million from a year earlier.
For all of 2012, sales to retail customers, as measured in kilowatt hours, fell 2.3 percent, which the company blamed on mild weather during the year. The full-year decline in sales to residential customers was 5.4 percent.
Southern has 4.4 million customers in a region that includes most of Georgia and Alabama and parts of Florida and Mississippi.
The shares rose 13 cents to $44.75 in morning trading. They have traded within a tight range over the past year, from a high of $48.59 in July to a low of $41.75 in November.