She was named as one of three cross country skiers who had failed drugs tests just as the news of her win was being toasted by the Russian team.
The Russians say they will file an appeal with the Court of Arbritration for Sport within the next few days.
Had the 30km result stood, Lazutina's victory would have equalled compatriot Ljubov Yegorova's haul of six cross-country golds.
Earlier in the week, Lazutina was barred from the women's relay for failing a blood test.
Her disqualification led to Russia's entire team threatening to leave the Olympics.
That threat was later dropped and the results of Lazutina's urine sample, which had to be matched with the blood test, did confirm her Darbepoetin doping offence after she was allowed to compete in the 30km classical cross-country.
Lazutina had set the fastest pace from the outset of the 30km race, which had a staggered start.
She crossed the finish line with her arms aloft in triumph in one hour 29 minutes nine seconds.
Italy's Gabriella Paruzzi who finished second in 1:30:57, will now be awarded the gold medal.
Italian team-mate Stefania Belmondo moves up from bronze to silver medal position and Bente Skari of Norway has been placed third.
Both Lazutina and Spanish cross country skier Johann Muehlegg tested positive for Darbepoetin, a drug not yet officially recognised as illegal, but very similar to banned substance EPO.
"We know that she is innocent and we are prepared to fight this doping conviction in court"
Russian team official Viktor Mamatov on Lazutina's case
Muehlegg and Lazutina have been ordered by the International Olympic Committee to return their medals, and accompanying Olympic diplomas.
Another Russian, Olga Danilova, who finished eighth in Lazutina's event, has also been disqualified for the exact same offence.
Because the athletes failed out-of-competition tests on 21 February, Muehlegg and Lazutina will still retain the medals they won earlier in the Games.
That means Muehlegg will leave Salt Lake with two of his three golds, and Lazutina with her two silver cross country medals.
Danilova, who won a gold and silver at the Games, will not lose a medal but will have to hand her diploma back.
IOC President Jacques Rogge said: "They may technically be champions with those medals, but I question their moral authority, and how they can claim to be Olympic champions in the full sense of the word."
Viktor Mamatov, Russia's chef de mission, countered: "We know that she is innocent and we are prepared to fight this doping conviction in court.
"We all know of the discrimination against the Russian team at these Games as we also know why this is going on.
"We all have heard rumours how everybody here is fed up with Russians winning in the Olympic Games, so now they are trying to put a stop to it at any cost."
Darbepoetin, a state-of-the-art drug which scientists estimate could be ten times more powerful than EPO, increases the level of haemoglobin - oxygen-carrying red blood cells - in the body, and so boosts endurance.
Secondary urine tests confirmed all three athletes had registered well above accepted levels of haemoglobin.