The attack outside the main police station in the city of Charleroi, around 60 kilometres south of Brussels left one of the policewomen with "deep wounds to the face" while the other was slightly injured, Belga news agency said.
Charleroi police said the attacker was shot and killed, while the two victims were out of danger.
Belgium has been on high security alert for months since suicide bombers struck Brussels airport and a subway station near the European Union's institutions on March 22, killing 32 people.
Belgian Interior Minister Jean Jambon condemned a "disgusting act in Charleroi" on his Twitter account and said the country's terror threat level -- currently at level three on a scale of four -- would be examined.
Belgian police have carried out dozens of anti-terror raids since the November 2015 attacks in Paris, planned in Belgium and involving Belgian extremists, which left 130 people dead.
Last month they arrested and charged a 33-year-old man, identified as Nourredine H., with attempting to commit "terrorist murder" and "taking part in the activities of a terrorist organisation".
Belgium is the main source per head of population of jihadist recruits going from European Union countries to fight with IS in Syria, causing deep concern that they will return home battle-hardened and even more radicalised.
The interior ministry said 457 Belgian men and women had gone or tried to join jihadists in the Middle East, including 90 who are missing or dead.
Belgium launched its first attacks against IS in Iraq in late 2014 as part of a US-led coalition. It joined a similar anti-IS operation in Syria this year.
In June Belgian authorities charged two men with terrorist offences amid reports of a planned attack on a Euro 2016 fanzone in central Brussels.
Belgium then beefed up security for its July 21 national day celebrations after a truck attack that killed 85 people in the French city of Nice on Bastille Day, July 14.
