Tess Macleod Smith, vice-president of media and publishing at Yoox Net-a-Porter Group, will leave the company next month.
Macleod Smith, former group publishing director at Hearst UK's luxury magazine titles, joined Net-a-Porter in February 2012 as its group publishing director and has led projects including the launch of print magazine Porter in 2014.
The business merged with Italian rival Yoox in 2015 to form Yoox Net-a-Porter Group.
In an email about her departure, Macleod Smith said that she had made the "difficult decision" to step down just before Christmas.
She added: "Seven years after setting up our global media and publishing division, and as Porter hits its fifth-year anniversary, having achieved its best year ever, it felt like an opportune moment for me to embark on my next adventure."
Macleod Smith said she would be "exploring a couple of opportunities in the fast-moving worlds of fashion and tech".
Yoox Net-a-Porter Group confirmed that Macleod Smith was leaving,but declined to comment further.