The limited passenger service began with three Brussels Airlines flights.
Brussels Airport CEO Arnaud Feist said the flights -- to Athens, Turin in Italy and Faro in Portugal -- are chiefly symbolic. The flight to Faro was the first flight to depart Sunday.
Effective Monday, Belgium's biggest airport should be back at around 20 percent of capacity and able to process 800 passengers an hour, Feist added.
Brussels Airport, which usually handled about 600 flights a day, served about 1.5 million people in February, the month preceding the attack. Feist said he hopes full service can be restored by the end of June or beginning of July in time for the summer vacation season.
Despite the partial reopening, Delta Airlines said Saturday it was suspending service between its Atlanta hub and Brussels until March 2017 "due to the continued uncertainty surrounding the airport's re-opening and weakening demand." It said it still plans to resume service between New York's John F. Kennedy airport and Brussels "once the airport provides clearance for international operations."
The coordinated bombings at the airport and a subway station in the center of Brussels on March 22 killed at least 35 people, including three Americans.
The main suspect believed to have helped execute the bombings at the airport remains on the run.
After being immediately placed on the highest alert level following the attacks, Belgium's security level has since been downgraded. Paul Van Tieghem, director of the office that evaluates threats to the nation, said after the attacks that there was no indication another attack was imminent but the threat was still serious and possible.