Tijani equalized into an empty net after a big howler by Karviná goalkeeper.
Jurásek then scored after Bořil's pass and Jurečka scored his first league goal this season from a penalty kick before the half-time.
Slavia scored two more goals in the second half. Chytil added fourth just two minutes after coming on the pitch and Wallem added the cream on top with his Panenka penalty late in the game.
After an international break Slavia travel to Pardubice (16 September) before returning home for the Prague Derby (24 September).
Mandous – Masopust (46. Ogbu), Holeš, Bořil – Tomič, Zafeiris (84. van Buren), Oscar, Wallem (77. Hromada) – Jurásek (68. Ogungbayi), Tijani (68. Chytil), Jurečka
Holec – Krčík, Bederka, Svozil (C), Fleišman – Bartl (74. Ražnatovič), Čavoš, Mikuš (26. Soukeník), Boháč (61. Papalelé) – Akinyemi (74. Doležal), Memić (61. Ezeh)