Bord Gáis Energy made a pre-tax profit of £46m for its British parent company last year, up 53% on the figure for 2015.
The energy firm's cash flow more than doubled to £84m as the company reported revenues of £781m.
Bord Gáis Energy is owned by Britain's Centrica, which said it made a return to profit growth last year as it benefited from volatile energy prices and colder weather.
Centrica also flagged the possibility of a dividend rise after two years of shareholder payout cuts.
The UK utility, which also owns household energy supplier British Gas, managed to stem a loss of customers leaving to competitors in the second half of the year after cutting tariffs.
Centrica lost 409,000 household energy customers in 2016, most of them in the early months of the year.
It reported a 4% rise in 2016 adjusted operating profit to £1.52 billion, compared with analyst expectations of £1.47 billion.
"Centrica enters 2017 a stronger company - with encouraging underlying momentum and positioned to deliver longer-term returns and growth," CEO Iain Conn said.
The utility said debt levels were expected to fall to £2.5-3 billion by the end of this year, a range that it said would allow it to raise its dividend payments.
Centrica reduced its annual payout in 2015 after its core business was hit by weak energy prices and lowered it again last year.
Its trading business benefited from volatility in the power market and with profits rising 144% to £161m.
