It has produced a list of 16 offenders -- and there are some big names in there, such as the singers Rita Ora and Ellie Goulding as well as original famous vlogger Zoella.
Today's naming and shaming of some of the biggest influencers who are in need of getting their transparency act together is at least a start. It's a step up from the ASA telling off the occasional campaign for not featuring an #ad or #sponsored on a post. The CMA have far heavier powers to fine -- and even, after court action, imprison.
A CMA exec was doing the media rounds this morning warning that the named stars must do better and that they have been served a very serious warning. There is a list in today's BBC report.
Suffice it to say that I know a few of the top names, and the "stars" from reality tv shows who make up most of the 16 names are a mystery -- but these guys have massive followings and need to be brought into line.
There will be many in adland who will wonder why more action has not been taken against these celebrities who can pocket hundred of thousands of pounds, and even millions, for telling the millions of followers that they like a particular product.
The rules for native advertising, for example, are very clear, and any publisher that breaks them is rebuked. Fonts have to be different, boxes need to be shaded in another colour and "sponsored feature" or words to that effect have to be prominent so a reader knows at first glance that the article is promotional.
The CMA claims that it wants influencer posts to be instantly recognisable, similar to promotional content, at first glance. That means #ad or #sponsored needs to feature prominently at the start of a post and not be buried in a series of hashtags.
It also means it is no longer enough to admit to commercial relationships in a social media biog, and each post related to a commercial relationship must be signposted.
That also goes for any mention of equipment or services that have been lent to the influencer without a contract to publicise them. The CMA is suggesting that a #freebie notification will suffice.
In other words, the days of not admitting a post was the result of a commercial relationship are over, and it is no longer enough to say a company is mentioned in a blog or that #ad was buried alongside twenty other hashtags.
To be honest, this is where we should already be. Influencers know they need to be up front, but they have tried to pay lip service to the rules.
The 16 that have been named and shamed today have been sent warning letters, and have been told in no uncertain terms that breaching these rules is a serious matter.
It's no longer the ASA these guys are dealing with, but the CMA -- the body that can raise huge fines and prosecute executives in a court of law.
Influencer marketing needs to be grow up and to be beyond reproach, because this is now getting serious.
The warnings have been stepped up considerably, and large fines will doubtless be in the wings for any star who keeps on ignoring the rules.