An RAF Reaper drone was involved in coalition missions near Baiji, the site of Iraq's largest oil refinery.
The MoD said the drone "successfully attacked" militants who were laying improvised explosive devices, according to the BBC.
Britain is one of about 40 nations involved in the fight against IS, which controls parts of Iraq and Syria.
Last week, Defence Secretary Michael Fallon said the UK would be sending more military trainers to Iraq. A dozen British trainers have already been deployed to work with Kurdish forces in the northern city of Erbil.
On Sunday, the US announced it was sending another 1,500 troops to Iraq.(KH)