The tech giant said there would be a "one-strike policy" banning those who violate new Facebook Live rules.
New Zealand Prime Minister Jacinda Ardern called the measures a "good first step".
In March the gunman live-streamed the attacks in New Zealand, where 51 people died.
Ms Ardern is chairing the summit with French President Emmanuel Macron. It aims to co-ordinate international efforts to stop social media being used to organise and promote terrorism.
Political leaders from Europe, Canada and the Middle East will meet senior representatives from companies such as Facebook, Google and Twitter, who will issue a joint "call to action" to cooperate on "transparent, specific measures" to eliminate terrorist material.
"The dissemination of such content online has adverse impacts on the human rights of the victims, on our collective security and on people all over the world," reads the pledge.
UK Prime Minister Theresa May will call for governments and technology companies to work together to prevent terrorist material being shared online.
Mrs May said the fact Facebook had to remove 1.5 million copies of the video was "a stark reminder that we need to do more".
Speaking ahead of the summit, the prime minister said the tactic of live-streaming attacks "exposed gaps in our response and the need to keep pace with rapidly changing technological developments".
She said: "My message to governments and internet companies in Paris will be that we must work together and harness our combined technical abilities to stop any sharing of hateful content of this kind."