Setting out his "comprehensive strategy" for how the UK will seek to tackle Islamic State, Cameron told the MPs more action was needed to tackle the group, which has claimed responsibility for attacks in Paris and against Russian civilians recently, while it extends its grip on Syria.
The Prime Minister said: "The threats to our interests and to our people are such that we cannot afford to stand aside and not to act."
MPs are expected to vote on whether to authorise air strikes in the next few weeks.
Labour leader Jeremy Corbyn is expected to oppose any intervention, but some of his MPs are expected to rebel in support of airstrikes.
However last night the shadow cabinet - including Corbyn, shadow chancellor John McDonnell and shadow foreign secretary Hilary Benn - was given a confidential briefing by intelligence and security chiefs on the full extent of the threat posed to the UK by the group, according to Huffington Post.
It follows the attacks in Paris earlier this month, which Islamic State has since claimed. At the time Cameron said the UK would do all it could to "support our friend and ally France and defeat this evil death cult".
Both France and Russia - which has also been targeted by Islamic State militants, who downed a passenger jet at the end of October - have been carrying out airstrikes in Syria this autumn.