The victory marks the 40-year-old's 13th medal in the Winter Olympics and his second one at Sochi. He won his first medal at the 1998 Winter Olympics in Nagano, Japan.
Wednesday's event was the first-ever Olympic mixed relay in biathlon. Bjoerndalen shared the win with teammate Bjoern Daehlie. He previously won the gold in the men's sprint biathlon on Feb. 8; the sprint medal made Bjoerndalen the oldest man to ever win a gold medal at the Winter Games.
Both Bjoerndalen and Daehlie have a total of eight gold medals.