After two semesters of studying medicine, he began his career as a designer in Ibiza on the popular hippie market of the island with a small stand of clothes that he had sewn himself.

Along with work outfits for Deutsche Telekom, Kempinski, Hotel Maritim [de], and Emirates Airlines, he also designed around 2,5 million suits for the TUI Group.

In 2004, Kretschmer founded the label Guido Maria Couture, with which he reached his creative focal point, designing cocktail dresses and evening gowns as well as the associated accessories.

His label is regularly represented on large fashion shows and celebrities such as Charlize Theron, Jane Seymour, Patricia Kaas, Iris Berben, Martina Gedeck, Jasmin Wagner, and Heino Ferch have worn his creations.

In 2013 and 2014, Kretschmer was a judge on Das Supertalent, the German instalment of the Got Talent franchise, alongside Dieter Bohlen, Bruce Darnell, and Lena Gercke.