The @UKAgainstISIL account will provide "updates on the UK government's ongoing work to defeat ISIL".
Four posts have been made since it was set up yesterday, including a video explaining the role the UK is playing in the fight to defeat the terror group.
The footage says Britain is "militarily removing territory from ISIL" and "cutting off ISIL finances".
One of the posts read: "To protect Britons at home we have disrupted ISIL-linked terror plots, stopped people wanting to do harm from reaching the UK.
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Islamic State, also known as the Islamic State of Iraq and the Levant (ISIL), often uses social media to spread its views.
A US study earlier this year had claimed there were at least 46,000 Twitter accounts operating on behalf of IS.
British forces have been carrying out airstrikes against ISIS militants in Iraq, but no action in Syria has been approved by Parliament.
There is speculation that British Prime Minister David Cameron will push for a vote to extend the UK's involvement when Parliament returns from its summer break next month.