Cappello's father was a Chilean journalist and former business executive with ITT and Hill & Knowlton. As a child Cappello lived in Puerto Rico and then moved to the US. He attended Duke University, was member of the US Court Tennis Team and completed his law degree from New York University in 1989. While at NYU Cappello served on the New York University Law Review. Cappello won the US Amateur Double Court Tennis National Championship in 1999.
Following law school Cappello worked for the law firms Cleary, Gottlieb, Steen & Hamilton in NYC and Philippi Yrarrazaval in Santiago, Chile. Cappello is now managing partner of the Private Advising Group PA, a Miami based law firm and was until January 2013 a principal shareholder of the firm Greenberg Traurig. The more important cases he helped to represent include Bush v. Gore, and the merger between Guidant and Boston Scientific. In 2013 he was named Lawyer of the Year in derivative and futures law from the Miami area by Best Lawyers. He was also named the Leading Lawyer of the Year in the Corporate/M&A – Latin America category at the 2013 Law Awards. His previous positions have included Executive Vice President, Corporate Secretary, and General Counsel of Patagon bank, where he engineered the sale of a controlling interest in Patagon to Banco Santander for more than US$750 million. Before that he was General Counsel and SVP of SKY Latin America.
Cappello has been involved in the creation of about two dozen start-up companies in Latin America and speaks on the subject internationally. Cappello has stated that governmental interference in Latin America is one of the largest roadblocks to the formation of the new companies. However, he has also said that access to the Internet is changing the access to business opportunities for Latin Americans, and that the spread of the Internet is allowing regional start-ups to become more frequent and successful. NPR called Cappello "a major high-tech investor in Miami", who advocates for "the phenomenal market growth rate in Latin America" and its effects on the economy of Miami.
Cappello was named a “Top 50 Entrepreneur” by Business Leader magazine and one of the “Most Influential Hispanics” in the areas of science and technology by Poder Magazine. Poder wrote of Cappello that, "Among his projects, he advises OpenEnglish, a leading online English language platform that has secured more than $150 million ... Cappello also founded Sauber Energy, a green energy company based in Florida, and Urbita, a travel site that leverages numerous languages with localized, regional knowledge to form a robust social network for travelers. He dabbles in brick-and-mortar, too. In Miami’s trendy Wynwood Art District, he cofounded The Lab Miami in 2012, an open, shared campus workspace where programmers, designers and the bootstrapped masses gather to hatch the next great idea."
He is also a founder of Ideame, a website described by the founders as attempting to attract more entrepreneurs and venture capital to small start-ups in Latin America. It has helped more than 200 businesses get off the ground. According to the New York Times, "While most Latin American crowdfunding sites are country-specific, Ideame is trying to become a top player for the entire region. It started at the same time in Argentina, Chile and Mexico ... Ideame registered 117,000 total unique visitors in July , according to comScore data. (The company did not exist in July 2011.)" He also cofounded Accelerated Growth Partners, an angel investors group in Miami.
Cappello is a member of the Global Advisory Board and Senior Advisor of Endeavor and the legal committee of the Latin American Venture Capital Association. He is also on the advisory board of the Pino Entrepreneurship Center at Florida International University, as well as the advisory board of the Institute of Global International Effectiveness at the Kelly School of Management, Indiana University.