It said second-quarter net profit jumped to 259 billion roubles (2.95 billion pounds), from 48 billion roubles in the year-earlier period and above a forecast of 228 billion roubles in a Reuters survey of analysts.
Gazprom's shares were up 1.1 percent after the results, outperforming the broader Moscow stock market <.IMOEX>, which was 0.8 percent higher.
Gazprom shipped more than 101 billion cubic metres of natural gas to the EU and Turkey in the first half of the year, up 6 percent year-on-year and accounting for around a 34 percent share of Europe's gas market.
It said its average gas export price rose by a quarter to 13,858 roubles per 1,000 cubic metres in the first half of this year.
Total sales in April-June increased to 1.83 trillion roubles, from 1.39 trillion roubles in the second quarter of 2017.
(Reporting by Vladimir Soldatkin; Editing by Susan Fenton)