Countess Maria Zofia Czartoryska née Sieniawska (15 April 1699–21 May 1771) was a Polish szlachcianka (noblewoman).

Countess Maria Zofia was daughter of Count Adam Mikołaj Sieniawski and Princess Elżbieta Lubomirska.

He was previously married to his cousin, Countess Johanna Katharina von Dönhoff (1686-1723).

Maria Zofia's stepdaughter Countess Konstanza von Dönhoff later married Prince Janusz Aleksander Sanguszko.

Among the candidates to the hand of one of the wealthiest women in Europe were Prince Charles de Bourbon-Condé, Count of Charolais, supported by France (Louis XV even invited Maria Zofia to Versailles); Portuguese infante Dom Manuel de Bragança supported by the Habsburgs (proposed as the next King of Poland, due to the tenets of the Löwenwolde's Treaty),[2] Jan Klemens Branicki, Franciszek Salezy Potocki, Jan Tarło and August Aleksander Czartoryski, who eventually won the competition, full of duels and speech encounters due to support of Augustus II, as the latter was afraid of increase of power of his opponents.