Dormracheva became the third athlete in these Olympics to win two individual competitions and the second to do so on Friday. Dario Cologna of Switzerland won his second individual cross-country skiing gold earlier in the day after French biathlete Martin Fourcade had also done so on Thursday.
With temperatures holding in the low 50s even though the sun had gone down on the biathlon course, Dormracheva defeated her closest rival by well over a minute.
Dormracheva missed one of the 20 targets on the shooting range, which added a minute to her score, and that gave her a final time of 43:19.6.
Selina Gasperin of Switzerland finished second, 1:15.7 behind. Gasperin had a perfect shooting performance, as did third-place finisher Nadezhda Skardino of Belarus.
Only five of the 78 contestants who finished the race made good on all 20 shots.
This was the third Olympic medal overall for Dormracheva, who earned the bronze in the 15-kilometer race four years ago.