The growth results were based on the AOP's Digital Publishers Revenue Index (DPRI) which, for the first time in five years, shared its headline results with the press. More detail on the revenue recorded in the fourth quarter was not available at the time of writing.
But a release added that display advertising in particular saw a 14 per cent increase year-on-year, and classified advertising a 4.3 per cent rise.
AOP also shared the findings of its Sentiment Index in the release, which it said "questions AOP members about how they anticipate the coming 12 months".
The Sentiment Index found that this year "digital media owners expect to reduce their focus on cutting costs and increase their attention on growing both advertising and non-advertising revenues".
The release adds that "63 per cent of respondents say launching new products or entering new markets is a high priority in the coming year", which is said to be an increase on the third quarter results.
These results refer to the responses from "board members" of the AOP, which according to the AOP site include more than 20 digital publishers.
AOP said the Sentiment Index results show "optimism is also on the rise among digital media owners".
"We know that the market is tough but optimism among digital media owners has been rising for the past five quarters," head of research and insight at AOP Tim Cain said in the release.
"What’s interesting is that historically this sentiment has tended to be conservative, with actual figures showing stronger growth than the industry had predicted. We see no reason to believe that this will not be the case again."
Speaking to Journalism.co.uk, Cain also highlighted the growth of online video revenue, which was said to have risen 64 per cent, year-on-year, which he said was "reinforcing" the findings of "other major forecasters".
The release adds that in the last five years, "online video has experienced the greatest growth, increasing almost 600 percent in total".
Speaking to Journalism.co.uk, Cain said that previously the data had just "been used by members of the organisation as a benchmarking exercise".
Now, after five years of collecting data for the DPRI, and three years for the Sentiment Index, with Deloitte, the AOP decided it had reached the stage where the data felt "robust" enough to be released publicly.