The photo-sharing social media site revealed in a post on Instagram that ads would "slowly begin rolling out advertising".
In June, the photo-sharing site revealed it would expand its ad proposition in the UK following a US trial "later this year". It also said it would roll out the service to Canada and Australia "in the coming months".
Instagram first launched ads in the US last November, pledging it would only run "ads that were engaging" and "felt natural in people’s feeds".
The US trial saw ads appear with a "sponsored" label, with the user able to hide the ad by clicking on a tab in the bottom right corner, or "Like" to leave a comment.
At the time, Instagram reassured users it would not change the terms and conditions of photograph ownership, stating: "As always, you own your own photos and videos. The introduction of advertising won’t change this."
Last month, Instagram rolled out three tools that will allow brands to monitor their performance on the fledgling ad network to "help brands monitor their posts and campaigns by providing information on reach, impressions, and engagement".