The Mirror says the redesigned papers are cleaner and smarter, with new fonts and colour palettes.
The multi-platform, seven-figure brand campaign reinforces this message under the banner #Madeuthink.
Initially, it will run for six weeks across print, outdoor, TV, digital, mobile and social platforms.
The first of the ads – which were developed by creative agency Quiet Storm – will run in paper and online on Saturday.
Lloyd Embley, editor-in-chief of the Mirror, said: “We have invested a lot of time and effort into creating a design which helps to remind readers why we are different from the rest of the tabloid market.
“Together with the brand campaign, we aim to show exactly what sets us apart.
“At the Mirror we don’t just print words, we believe in them.
"We support causes through conviction not self-interest and we are passionate about setting the news agenda.
"Of course, we still have a sense of fun and frivolity - but we have a sense of social responsibility too.
“There's one thing which really makes the Mirror stand out from the tabloid crowd - we have a brain and so do our readers. And that's the message we're driving home here.”
Simon Fox, Trinity Mirror’s chief executive, said: "This is an exciting time for the Mirror across our print and digital platforms.
“We believe that we are the news brand which best reflects the mood of the country right now and which understands the needs and desires of the hard working families of Britain.
“For the proof, you only have to look at the circulation trends and the online growth the Mirror has produced this year.
“The redesign, coupled with our brand campaign - the first for 10 years - will enable us to further build on this momentum."
