The women officers' injuries are not life-threatening.
The assailant is said to have shouted "Allahu Akbar" ("God is greatest" in Arabic) during the assault outside the city's main police station.
Belgian Prime Minister Charles Michel told broadcaster RTL by phone: "Initial indications very clearly point towards terrorism."
Reports say the prime minister has cut short his holiday in the south of France and will return to Belgium for a meeting of the National Security Council on Sunday.
Charleroi was used as a base by some of the jihadists involved in the attacks on Paris in November 2015 and Brussels earlier this year.
Belgium has been on edge since suicide bombers attacked an airport terminal and a metro station in the Belgian capital on 22 March, killing 32 people and injuring many more.
The Belga news agency said one of the policewomen who was targeted suffered minor injuries, but the other had to receive treatment for serious wounds to her face.
Both were said to have been in a guard post set up to provide extra security for the police HQ.
Another officer, who was nearby, shot the attacker.
A man shot by police after he attacked two officers with a machete in the Belgian city of Charleroi has died.