Poland's Justyna Kowalczyk, who has won the last three World Cup titles and was second in the overall standings, had slight hopes of catching her rival but her performance on the day was not good enough.
Bjørgen, a triple Olympic champion in the 2010 Vancouver Games, has now won 55 World Cup races and three titles, after previous success in 2005 and 2006.
Run-away leader Dario Cologna, of Switzerland, was already assured the overall title going into the final men's race.
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