Jose Guillermo Castillo has decades of experience in government, financial management, international trade negotiations and strengthening relations between the private sector, governments, and NGOs. After retiring as CEO, Castillo is currently director of Castillo Hermanos, an industrial conglomerate founded in 1886 with more than 22,000 employees. He is also chairman of GTC Investments, vice chairman of GTC Group, and executive in residence at the John Ward Family Business Center at Northwestern University.

Prior to these positions, he was president of the 2020 Foundation, a technical institution providing analysis and proposals for legislation to strengthen long-term governance. He was a member of the International Commission of the Coordinating Committee of Agricultural, Commercial, Industrial and Financial Associations and chairman of the Economic Commission.

Castillo served Guatemala as ambassador to the United States from 2004 to 2008, minister of Economy from 1999 to 2000, and deputy minister of Economy from 1997 to 1999, responsible for foreign trade affairs, the Central American Integration Process. He also served as director of the Guatemalan Monetary Board.