Profits for 2012 amounted to 1.183 trillion rubles (USD 38.17 billion) compared to 1.307 trillion rubles (USD 42.2 billion) in 2011, the leviathan Russian company said in a statement.
Gazprom said that during the year net sales of gas fell by six per cent as deliveries to Europe and other foreign countries rose just two per cent while those to the ex-USSR states fell 17 per cent.
The fall in profits for the company, which controls around one quarter of the world's gas reserves, was the first in a decade.
The earnings left Gazprom with the third biggest profits of any cooperation worldwide in 2012 after ExxonMobil which posted USD 45 billion of profits and Apple with almost USD 42 billion.
However this still represented a downward trend from 2011 when its mega profits made it the world's most profitable firm ahead of both ExxonMobil and Apple after currency conversions.
The state-controlled company, which was created out of the USSR gas ministry, is a cornerstone of the modern Russian state under President Vladimir Putin and a key earner of foreign currency.
There has also been mounting criticism of Gazprom's pipeline-based delivery strategy at a time when liquid natural gas is becoming more in demand, and concern that it is too late to the shale gas boom.
The firm's chief executive Alexei Miller told state media last month that the "shale revolution" was "a bubble" and that Gazprom did not intend to shift strategy.
However President Vladimir Putin was more equivocal last week, saying Gazprom needed to be "as attentive as possible" to growing shale gas production worldwide.
The option would bring the company into line with EU energy rules as Brussels works actively to reduce its dependence on Russian gas.
Analysts at UBS wrote this week that Gazprom's current situation was marked by "production decline (and) a glut of gas in a highly competitive gas market".
VTB Capital meanwhile described 2012 as an "annus horribilis" in which Gazprom lost domestic market share in a macro and regulatory environment that "could hardly have been worse".
