The cross-country legend, 37, signed off in style after a glittering Olympic career as she won 1min 49.5sec ahead of Finland's Krista Parmakoski, as Stina Nilsson of Sweden took bronze.
After the final event of the Pyeongchang Winter Olympics, Norway and Germany both have 14 gold medals. But the Norwegians have a record 39 medals overall, compared to Germany's 31.
Bjørgen became the most successful Winter Olympian of all time earlier in the Games, when she finished third in the team sprint free.
Her bronze with Maiken Caspersen Falla put her on 14 Olympic medals, outstripping fellow Norwegian Ole Einar Bjørndalen, who has 13 in the biathlon.
Bjørgen is also the second most successful woman at either the Summer or Winter Games, trailing only Soviet gymnast Larisa Latynina with 18 medals.
Norway, a country of 5.2 million people, have enjoyed a barnstorming Olympics, breaking the United States' 2010 record of 37 medals at a single Winter Games.