Ultimo Brands International, the holding company of MJM International, saw sales grow by 24% last month compared with December 2012. That month had seen a 4.8% sales drop compared with the same month in 2011.
Ultimo cited a strong final week in December last year as being key to the surge.
Ms Mone said: "Breaking our December sales record is a great way to start the year, but perhaps more significantly signals a new phase of growth and success for the brand."
Ultimo is poised to launch a spring/summer collection, with a campaign featuring Abbey Clancey. It is also recruiting an e-commerce manager to manage its revamped website.