Frith is to return to Bauer in the New Year as editorial director - lifestyle, providing "strategic vision" across a range of brands, including his old title FHM, along with Grazia, Zoo, Yours and Empire.
He acted as editor-in-chief of Heat magazine for almost a decade up to 2008, resigning two months after German publisher Bauer acquired the title.
During his time at Heat, he increased the readership from just 65,000 to 590,000, but
quit to write a book about his experiences editing the celebrity magazine.
More recently, Frith acted as editor of Time Out until resigning in the summer.
From next year, he will be responsible for improving the editorial quality of Bauer's portfolio of lifestyle titles and digital brands, including measures to increase audience engagement.
"I'm delighted to be joining Bauer Media in this newly-created role," said Frith.
"The company is home to some legendary brands and exceptional editorial teams and I can't wait to get started!"
Bauer has also appointed Abby Carvosso, currently its head of magazine sales, to the newly-created role of managing director of lifestyle and advertising, with immediate effect. Carvosso will lead an "integrated approach" across the lifestyle editorial and commercial operations.
Bauer Media chief executive Paul Keenan said: "These appointments are indicative of Bauer Media's continued commitment and investment in the delivery of world-class editorial products and commercial operations. Mark and Abby are both very strong, very talented leaders and will play an important part in the further development of our vision for the future."