María Gracia Rubio began her professional career at the Pérez Llorca firm in 1985. In 1988, she joined the Legal Services of the National Securities Market Commission (CNMV), and in 1994, she decided to leave the CNMV to establish her own firm specialized in financial regulation. This firm, after merging with other national firms, was absorbed by Baker & McKenzie in 2001. From then until December 2014, María Gracia was responsible for the Financial Regulation team in the Madrid office of Baker & McKenzie, in addition to being a member of the Steering Committee of the European Financial Services Group until 2012.

In 2006, María Gracia was appointed by the European Commission as a member of the European Securities Markets Experts Group for an initial period of two years, which was later renewed, with the aim of advising the European Commission on the reform of securities market regulation. Furthermore, between 2001 and 2012, she was part of the Legal and Tax Committee of the European Venture Capital Association (EVCA) and the Legal and Tax Committee of the Spanish Venture Capital Association (ASCRI).

In December 2014, María Gracia left Baker & McKenzie to resume her professional activity through her own firm, Rubio de Casas Abogados (RDC Abogados), expanding her advisory services to include the regulation of internet-based financial services. Since then, she has advised various entities offering online financial services, including several crowdfunding platforms, broker-dealers (including the first-ever Spanish robo-adviser), and consumer credit institutions. She is also an independent Director of JB Capital Markets, S.A., and of Sociedad de Valores and AyG Banca Privada.