The 26-year-old, who finished 12th during the only other World Cup round this season in America, produced a total of 95.00 on his opening run in the final.
And that was not to be beaten as he led a Norwegian one-two with Staale Sandbech's first-run effort of 92.75 enough for him to place second.
Sven Thorgren kept the top-three all Scandinavian as the Swede also broke the 90-point barrier with a second run of exactly 90.00 for third with Canada's Sebastien Toutant fourth with 86.75.
The win puts Horgmo at the top of the overall men's slopestyle World Cup standings ahead of the third and final round in Sierra Nevada with a total of 1220points.
Roope Tonteri, who was 11th in Spindleruv Mlyn, is second overall with 1040 points before Sandbech and Charles Guldemond, who won the World Cup opener but was absent from the Czech Republic, in joint third with 1000.
Meanwhile Finland's Enni Rukajarvi won the ladies' event but a third place for Kjersti Buaas behind Sina Candrian gives her the overall lead ahead of the final round of the season.
Rukajarvi scored 89.75 on her first run for victory with Candrian managing 81.50, also with her opening effort, for second ahead of Buaas while Britain's Jenny Jones placed sixth out of six in the final.
Buaas, second during the season opener, has 1400 points to her name at the top of the overall slopestyle World Cup standings, 400 ahead of Rukajarvi who was competing on the circuit for the first time this season.
Rukajarvi is level on 1000 points with Jamie Anderson, who didn't start in the Czech Republic having won the season opener, before Candrian in fourth overall with 815.20.