Even before the vote took place, the six F-16s took off from a Belgian air base headed for Araxos in Greece, a staging post on their way to Jordan, where they will be based from Saturday.
"The six F-16s will participate in the military operation ... requested by the government of Iraq," Belgian Defence Minister Pieter De Crem told parliament.
Belgium has also sent two military transport planes, a C-130 and an Embraer, to take 120 pilots and support staff along with supplies needed for the mission.
Parliament voted 114-2 in favour of sending the Belgian contingent, initially for a period of one month which could be extended.
Washington has organised a coalition of countries to counter Islamic State, which has seized large swathes of territory in Iraq and Syria, reaching up to the border with NATO member Turkey.
Britain's parliament also voted on Friday to approve air strikes against Islamic State militants in Iraq.
Until this week France was the only Western country to answer President Barack Obama's call. But Australia, Belgium and the Netherlands have all joined since Monday and Denmark announced on Friday that it too would send planes.
Most Western countries are limiting their participation in air strikes to Iraq, however, not Syria, where the United States and Arab allies have attacked Islamic State targets.
Two Belgian Air Component F-16A's perform a split break after receiving fuel from a USAF KC-10 Extender aircraft.