A blunt Rögle side conceded two goals in 21 seconds just over halfway through the match in Plzen.
And the uphill battle was too much.
Plzen, runners-up in the Czech league last season, added two more goals past Rögle goalkeeper Arvid Holm in the third period.
Rögle, who lost to Skellefteå in the Swedish Championship final series this spring, was lacklustre in the CHL opener, the tournament the Ängelholm side won in 2022.
The other three Swedish teams, reigning CHL champions Frölunda, Skellefteå and Växjö, play their opening matches on Friday.
Rögle remain in the Czech Republic, where Dynamo Pardubice await on Saturday.
