Kostadinov studied Fashion Design at Central Saint Martins completing his BA and MA. In February 2016, Kostadinov was the first Menswear student to be awarded the New Gen Men British Fashion Council Support directly after graduating. His debut collection was presented at London Collections: Men in June 2016. In November of the same year Kostadinov was appointed by luxury British heritage brand Mackintosh, taking the helm at their new designer line, Mackintosh 0001. The collection was shown during Paris Fashion Week in January 2017.

Kostadinov has worked closely with Dover Street Market since his graduation, and continues to create in-store installations for Dover Street Market London, Ginza and New York. For the launch of his Spring/Summer 2017 collection he partnered with Commes Des Garçons Trading Museum for an installation during Paris Fashion Week. Earlier this year he was announced as one of Forbes Europe’s 30 under 30 within The Arts category.
For the exclusive launch of his Autumn/Winter 2017 collection, The Broken Arm played host to a window display by Kostadinov. The designer has collaborated with Japanese brand Asics, a first for the sporting label, on footwear for his Spring/Summer 2018 collection and will continue the partnership into Autumn/Winter 2018.