Former Heat editor Mark Frith is stepping down after two and a half years as editor of Time Out London.
Time Out chief executive David King said: "Mark has helped us through a period of huge change. He has been a great ambassador for the magazine and I have really enjoyed working with an editor with such a strong, commercial focus. His impact has been substantial and we wish him well".
Frith said: "I've loved my two and a half years at Time Out and am over-the-moon with the success we've had but I'm very ambitious and feel now is the right time to take on a new challenge. To leave on the high of our second PPA Magazine Of The Year win is just perfect."
Tim Arthur becomes acting editor when Frith leaves at the end of this month.
Weekly sales of Time Out have declined in recent years from 76,356 in the first half of 2008 to 55,316 in the second half of 2010.