Macken joined Haymarket Media Group as a sales executive in 1988, and after numerous senior positions in the company became the managing director of the business division in 2011.
Macken's responsibility included leading the group's evolution from a magazine business into a digitally-led operation, and overseeing the extension of market leading titles into events like Media 360 and Brand Max, and various awards.
Macken said: "I can honestly say I have loved working at Haymarket but after such a long time in one company it really is time to move on. When the business moved from Hammersmith to Teddington, I had a particularly long commute.
"During all my years at Haymarket, I have worked on or managed virtually every B2B brand and division, and I am very proud of HBM’s very many achievements. I feel privileged to have worked with so many talented people for so long."
Kevin Costello, chief executive of Haymarket Media Group said: "I am extremely grateful to Jane for her significant contribution to Haymarket over the years and her excellent leadership of the business division in particular.
"Jane has been instrumental in helping me shape Haymarket for the future as we transition the business from a print magazine company to a specialist international media company in our chosen markets.
"Jane’s knowledge and experience in B2B media is second to none, and her background of leading the business to profit growth from digital, data and events means she leaves HBM in great shape for further growth in the future. I am sorry to see her go."
Media Week is part of HBM