Newbold replaces Neshat Ahmed, who was only promoted to the position of managing director in May.
Ahmed, who took over the running of Emap Fashion from Tony Harris, former managing director of Emap Fashion, Emap Computing and Emap Media, has left the company to take a career break, a spokeswoman said.
Ahmed oversaw the launch of cutting-edge fashion exhibition 40掳 as event director, and was promoted to deputy managing director in 2000.
Newbold joins from Emap Elan Enterprises, where he was also managing director.
Ahmed's exit comes on the heels of the departure of Emap Digital managing director Jerry Perkins, who quit his position after 12 years with the company to "seek new opportunities".
Perkins joined Emap in 1989 as a sales executive on Q magazine. He joined Emap Digital in April 2000 to launch Emap's music and entertainment websites including, among others, Kissonline.com and Smashhits.Net.