[citation needed] Maria Theresa married Henri, comte de Chambord, the posthumous son of Charles Ferdinand, Duke of Berry, younger son of Charles X of France, by his wife, Princess Caroline Ferdinande of Bourbon-Two Sicilies, daughter of Francis I of the Two Sicilies, by proxy on 7 November 1846 in Modena and in person on 16 November 1846 in Bruck an der Mur, Styria.

Maria Theresa had been chosen as Henri's wife by his father’s cousin Marie-Thérèse-Charlotte of France.

Marie-Thérèse sought to ally the exiled French Royal Family with the House of Austria-Este for several reasons: it was Roman Catholic and the only royal family not to have recognized the July Monarchy of Louis-Philippe of France.

After Henri's death on 24 August 1883, Maria Theresa and a minority of Henri's supporters held that Juan, Count of Montizón, as senior male descendant of Louis XIV, was his successor.

[citation needed] Maria Theresa was instrumental in building a crypt for the French Royal Family at the Church of the Annunciation of Our Lady on Castagnevizza in Görz (now in Nova Gorica, Slovenia).