Speaking alongside Hollande at Elysee Palace during a visit to Paris, Cameron said he would set out in Parliament a comprehensive strategy to combat the dreaded terrorist outfit later this week.
"I have offered President Hollande the use of RAF Akrotirifor French aircraft engaged in counter-Isil operations and additional assistance for air-to-air refuelling," Cameron said.
"The United Kingdom will do all in its power to support our friend and ally France to defeat this evil death cult," he said.
"We must also do more to defeat ISIL in their heartlands in Syria and Iraq. Later this week in Parliament I will set out our comprehensive strategy for tackling ISIL," he said.
"I firmly support the action President Hollande has taken to strike ISIL in Syria and it is my firm conviction that Britain should do so too. Of course, that will be a decision for parliament to make," he added.
Cameron is also set to announce two 5,000-strong rapid action "strike brigades" to be created by 2025 to tackle with growing terror threats.
The extra spending will include a new fleet of marine patrol aircraft.
Writing in the SDSR's foreword, Cameron said over the course of this Parliament "our priorities are to deter state-based threats, tackle terrorism, remain a world leader in cyber security and ensure we have the capability to respond rapidly to crises as they emerge".
"Painful decisions were made five years ago, the defence budget was in a mess. Now we have a stable economy we've made a decision to spend more on defence and less of welfare," UK defence secretary Michael Fallon was quoted as saying by the BBC.
The SDSR is also expected to commit the UK to purchasing 138 F35 Joint Strike Fighter aircraftover a period of time.
Nine Boeing P8 sea patrol aircraft will be used for maritime surveillance, anti-submarine and anti-surface ship warfare.