One officer was stabbed in the neck and another in the stomach, while a third officer who arrived at the scene in Schaerbeek district suffered a broken nose, Belgian broadcaster VRT reports.
The attacker was shot in the leg and taken away by ambulance.
Belgian media report that Hicham D is known to Belgian police and is believed to have links to jihadists who traveled to Syria to fight.
"We have reason to believe that the incident was a terrorist attack," a spokesman for the Belgian federal prosecutor's office, Eric Van Der Sypt, said.
The attack happened near a main road in a region linked to previous terror attacks.
Belgium has been on high alert following attacks in Brussels on the airport and the city's metro system in March, which killed 35 people and injured more than 300.