Marcelo Castelo began his career at Unilever in 1998. By early 2000, he became a cofounder of F.biz, a digital advertising agency, which was sold to WPP in 2011. In 2003, he jump-started the mobile business division of F.biz, leading the Brazilian mobile market. He has rendered mobile marketing services to world-class clients such as Unilever, PepsiCo, Heineken, Kraft and Motorola. When F.biz spun off its mobile division as MUV in 2015, he assumed the role of CEO. He is the first Brazilian awarded in the 40 Under 40 list from Advertising Age; he was also honoured with the Brazilian Mobile Market Personality award. He served on the board of LATAM Mobile Marketing Association (MMA) for many years.