The Belarusian, who also won the 12.5km pursuit and 15km individual titles, took the lead early and never looked back, making only one mistake on the shooting range and skiing way too fast for the opposition to catch up.
Gabriela Soukalova of the Czech Republic took silver 20.2 seconds behind after she also made a mistake on the range.
"I am thankful to the people who support me. Without their support it'd be harder," Domracheva told a news conference.
"I was hearing 'Dasha, Dasha' from the tribune.
"Russian family, Belarusian family. All these nations, Russians, Belarusians, we are like brothers and sisters. For me, I feel this country is really native for me," she added.
"Maybe it sounds strange but it does not feel like I did something special. I did it with love."
Domracheva's dominance meant her rivals were racing for silver.
"I thought she was going to win today, she was so strong in the last races I did not believe somebody could be faster than her," said Soukalova, whose mother Gabriela Svobodova won silver at the Sarajevo Games in 1984 as a cross-country skier.
"I didn't race against her today, I thought it would be better to race with just myself."
Norwegian Tiril Eckhoff won the bronze, 27.3 seconds off the pace, after outsprinting German Evi Sachenbacher-Stehle in the final straight.
"She skies like a dancer," Eckhoff said of Domracheva.
The champion liked the comparison.
"To be honest I really like to dance, it's my second favourite occupation," Domracheva said with a smile.
Several athletes, including Norway's Tora Berger, crashed on extremely soft snow following a day of fog and light drizzle.
"In the last loop, I just thought I had to stand up in the (downhill) curve because I had seen Tora had fell down in that descent in the first loop and she is a good skier," Eckhoff told a news conference.
The men's race, which had been scheduled for 15:30 local time, was postponed because of poor visibility but the women's event went ahead as the skies cleared.
The snow, however, was mushy, favouring lighter athletes like Domracheva.
Norway's Ole Einar Bjoerndalen holds the record for most biathlon gold medals at a single Games with his four from the 2002 Salt Lake City Olympics.
Domracheva, now her country's most successful Olympic athlete, will also take part in the relay, although Belarus are not the favourites.
Domracheva said she had yet to decide whether she would take part in the mixed relay, where Belarus have very little chance of a medal.
- Sports & Recreation