The advertising watchdog is investigating Instagram influencer Mrs Hinch over concerns that she did not label posts plugging cleaning products as ads.
Sophie Hinchliffe, 29, from Essex, gives cleaning advice to her 2.5 million social media followers.
The Advertising Standards Authority (ASA) confirmed it received three complaints in April concerning the labelling of ads within her Instagram posts.
The posts included the products Flash and Febreze, both owned by Procter & Gamble.
Under advertising rules, influencers must make it clear in such posts that they have been paid or rewarded to promote, review or talk about a product in their social media feeds under consumer protection law.
It is understood that Ms Hinchliffe was given advice by the ASA on two occasions prior to the investigation on how to stick to the rules.
An ASA spokeswoman said: “I can confirm that we received three complaints in April about Mrs Hinch’s Instagram posts concerning the labelling of ads (where she was posting about products including Flash and Febreze) and are currently investigating.
“We will publish our decision in due course.”
Ms Hinchliffe said: “I take the responsibility that comes with having a large social media following very seriously, and, for me, being authentic and transparent is incredibly important.
“I’m fortunate that brands want to work with me, but I only collaborate with those that I genuinely like and would recommend to people.
“I continue to learn a lot, but feel my community are clear about any content that is part of a commercial partnership, and that which isn’t.
“In fact, I’m overly cautious when it comes to these guidelines and will continue to be.”
Mrs Hinch’s new book, Hinch Yourself Happy, has topped Amazon best-seller lists.