The Advertising Standards Authority received 29,554 complaints, down 7.9% from the previous year, while data suggests that only 17% of the public saw problem ads during the year, down from 22% in 2013.
But the number of ads that were changed or withdrawn as a result of the regulator shot up 32% to 4,584. The ASA said this was thanks to a "rebalancing from complaints-led work towards more proactive interventions in markets where consumers are facing harm" such as on broadband pricing, and guidance for vloggers on the disclosure of paid endorsements.
More than twice as many internet ads as TV ads generated complaints (8633 compared to 3920) but TV caused the greater number of individual complaints.
Broken down by sector, finance saw a 78% rise in complaints, driven largely by Moneysupermarket’s "Epic strut" ad – the most complained about of the year.
But the alcohol sector appears to be largely fulfilling its obligations; complaints fell 37% to 118 in relation to 90 ads.
The ASA's chief executive, Guy Parker, said: "The ASA’s ambition is to make every UK ad a responsible ad and recent changes show how our regulation is becoming more proactive and having more impact.
"Alongside our important work resolving consumer complaints, we’ve taken proactive action in areas that make the biggest difference for the public. As well as the record number of ads changed or withdrawn, the volume of our compliance work has trebled to almost 5,500 cases.
Parker said that the figures showed why protecting consumers, especially children, online was an urgent priority.
"In 2016, we’ll be implementing changes to broadband pricing, as well as examining gender stereotyping in ads, and exploring ways to reduce children’s exposure to ads for age-restricted products in social media."