SAO PAULO, June 21 (Reuters) - Brazilian pop star Anitta has joined Latin American financial start-up Nubank as the seventh member of its board of directors, in an unusual signing for a bank.

Born in a Rio de Janeiro slum, Anitta has become one of the most prominent Brazilian artists, nominated four times for Latin Grammy awards and gaining 54 million followers on Instagram.

Nubank said in a statement on Monday that Anitta, whose latest single is called "Girl From Rio" in a nod to the 1960s hit "The Girl From Ipanema", will help the bank enhance its services and products to low-income consumers.

The bank's CEO and founder David Velez said that the 29-year-old pop singer will bring a deep knowledge of marketing to consumers in Latin America.

With 40 million clients in Brazil, Mexico and Colombia, Nubank was valued at $30 billion in a recent funding round led by Warren Buffett's Berkshire Hathaway. (Reporting by Carolina Mandl; Editing by Alexander Smith)