Sikora finished ahead of Norwegian pair Ole Einar Björndalen and Emil Hegle Svendsen, who retained the lead in the overall standings.
He was second after the sprint and with a perfect shoot climbed to the top of the leader board.
Svendsen and Frenchman Simon Fourcade, who eventually came in fifth behind Germany’s Michael Greis, each missed two of their shots.
Sikora missed a shot in the last shoot but with a strong skiing performance was able to hold on to win the event. Björndalen was able to pass his countryman Svendsen and pip him to the runner up spot, only 2.5 seconds behind the lead.
The best placed Swede was Björn Ferry who just edged into the top ten positions after having wallowed in 36th place.
The World Cup biathlon event in Östersund continues on Sunday.