He holds a degree in Law, has been a professor in the field of Roman law at the University of Barcelona for more than 30 years and is currently working as a Partner of Counsel for the firm MES Advocats i Gestió. During his professional career, he has held various management positions, such as Deputy General Manager-Secretary General at "la Caixa" in Barcelona, Deputy General Manager at "la Caixa" and Director of the Fundació Centre d'Estudis Internacionals of the University of Barcelona, among others. He has also presided the Fundació Privada Hospital de l'Esperit Sant, Abertis Logística and has been a member of the Economic Affairs Council of the Archbishopric of Barcelona. He has also been a member of the Board of Directors of several companies and a member of the Board of Trustees of several institutions. From 2002 to 2019, Millet presided the Pere Tarrés Foundation and represented this institution on the Board of Trustees of the Ramon Llull University Foundation. He was Chairman of the Board of Trustees of the URL (2020-2024).

He joined the Honorary Committee in December 2024.