Andres Ambuhl gave Switzerland the lead with a powerplay goal at the end of the first period before Nino Niederreiter doubled their advantage in the second.
Jiri Hudler scored twice to bring the Czech Republic back into the game, but the Swiss turned up the heat in the third, firing three goals without reply to move to the top of the group on eight points.
In the day's second game, an ineffective Sweden limped to a 2-1 victory over Belarus.
The Swedes fell behind in the first period but Oscar Lindberg levelled the scores when he netted five minutes into the second. Fredrik Pettersson scored the winner for Sweden with eight and a half minutes left.
Co-hosts Finland endured a frustrating first period against France in Helsinki but Juhamatti Aaltonen created one goal and scored another to turn the game in their favour and they ran out 3-1 winners.
Pierre-Edouard Bellemare pulled a goal back for France at the start of the third period but Ville Viitaluoma netted eight minutes later for the Finns to put the game beyond reach.
In the early game in Helsinki, Germany twice threw away the lead before losing 3-2 to Slovakia, Tomas Zaborsky scoring twice in the third period to help his team to victory.