Eason is currently deputy editor of House Beautiful magazine, but held the post of acting editor at Cosmo Bride from August 2005 to May 2006.
She joined The National Magazine Company in March 2001 as deputy editor of CosmoGIRL! Magazine, after previously working at Sugar, 19, Top of the Pops and B magazines.
Matt Salmon, publishing director of the Lifestyle Group at NatMags, said: "As the acting editor for [Cosmo Bride] in 2005/6 [Miranda] demonstrated that she has both the vision and passion for delivering success in this dynamic magazine genre."
Eason will take up her new editorship on December 17.
She said: "I'm thrilled and excited to be appointed as editor of Cosmopolitan Bride, the magazine for brides-to-be who are planning a contemporary wedding. I am very much looking forward to working with the team to develop the title over the coming months."
NatMags announced earlier this week that it was to launch a 30-day fashion and beauty festival across the UK next year, featuring in-store shopping competitions, fashion shows, blogs, cocktail parties, fashion workshops, tickets to events and consumer makeovers.