Domracheva became the first athlete at the Sochi Games with three golds and they have all come in individual races. She won the 10-kilometer pursuit race as well as the 15-kilometer competition earlier in the Olympics.
Belarus had just one gold to its credit from all previous Winter Games until Domracheva went to work on the biathlon course.
There were 29 competitors in Monday's race, which was able to get under way on schedule after the fog that had postponed the men's mass start race finally lifted.
All the contestants started at the same time and when the skiers had completed their first 2.5 kilometers and headed into the shooting range, Domracheva was a second behind sprint specialist Anastasiva Kuzmina of Slovakia.
Kuzmina won the individual sprint to open the biathlon events at the Olympics, but she faded Monday while missing five shots and finished 27th.
Domracheva shot cleanly in her first five attempts and quickly moved into the lead for good. Gabriela Soukalova of the Czech Republic fell in behind Domracheva heading out of the first shooting station and they remained 1-2 all the way to the finish line.
Neither biathlete missed a shot through the first three rounds and both missed once in the fourth round, requiring them to ski a 150-meter penalty lap. With her lead having steadily grown through the race, Domracheva eventually finished 20.2 seconds in front of Soukalova.
The bronze medal went to Tiril Eckhoff of Norway, who crossed the line a second in front of Germany's Evi Sachenbacher-Stehle.
The men had been scheduled to compete in their 15-kilometer mass start race on Sunday, but that evening competition had to be postponed because of fog. When the contestants returned to the course early Monday to try again, the fog was still there -- reducing visibility to less than half the length of a football field.
The men's race was postponed again and will now be held, weather permitting, on Tuesday. Ole Einar Bjorndalen of Norway will make another try in that race to win a record 13th Olympic medal. France's Martin Fourcade will also attempt to match Domracheva with three gold medals from these Games.