Norwegian Boe finished second behind Fourcade of France in last year's World Cup, although this season he had won just once heading into the first of three final events in Oslo.
But in the 10km sprint Boe shot clean en route to coming home in 24:53.3 minutes, beating Fourcade to the top step of the podium by 13.6 seconds.
While Fourcade fiished second with one penalty, Russian Anton Shipulin also shot clean to finish third, 21.3 behind Boe.
While Fourcade remains untouchable at the World Cup summit on 1282 points, 429 ahead of second-place Shipulin, the win sees Boe advance his hopes of finishing third.
Boe now has 760 points to his name and is 53 ahead of German Arnd Peiffer, who was 14th in Oslo, with just two events remaining.
This was the final sprint event of the season with Fourcade winning on 484 points, Austrian Julian Eberhard ending up second on 345 and Emil Hegle Svendsen third with a score of 276.
Read the original article on Eurosport: Boe beats Fourcade to sprint success in Oslo