Twitter says it has suspended more than 125,000 accounts since mid-2015 “for threatening or promoting terrorist acts”.
In a blog, the US-based firm said the accounts “primarily related to ISIS” (the so-called Islamic State group).
“We condemn the use of Twitter to promote terrorism,” it said, adding that it had increased its report reviewing teams to react faster.
Twitter has more than 500 million users around the world.
“We have already seen results, including an increase in account suspensions and this type of activity shifting off of Twitter,” the company said.
It added that it was co-operating with law enforcement bodies “when appropriate” as well as other organisations.
Governments around the world – including the US – have been urging social media companies to take more robust measure to tackle online activity aimed at promoting violence.
In December, US politicians put forward a bill that would force such companies – including Twitter and Facebook – to report any apparent terrorist activity they find.
EU officials have also been calling for talks with major social media firms to discuss the issue.
In March, Facebook revamped its “community standards” to include a separate section on “dangerous organisations”.
It said it would ban groups promoting “terrorist activity, organised criminal activity or promoting hate.”