Tsarevna Catherine Ivanovna of Russia (20 October 1691 – 14 June 1733) was a daughter of Tsar Ivan V and Praskovia Saltykova, eldest sister of Empress Anna of Russia and niece of Peter the Great. By her marriage, she was a Duchess of Mecklenburg-Schwerin.

Catherine was born in Moscow and baptized at Chudov Monastery; her godparents were her uncle Tsar Peter I and her great-aunt Princess Tatiana (daughter of Tsar Michael I. She was the third of five daughters, but the early deaths of her older sisters Maria (on 23 February 1692, aged three) and Feodosia (on 22 May 1691, aged one) left her as the eldest child of her parents. Two more sisters were born later: Anna, the future Russian Empress, and Praskovia (born 14 October 1694 - died 19 October 1731).

Catherine (reportedly the favorite child of her mother), spent her childhood in her mother's state of Izmaylovo, also the birthplace of her paternal grandfather Tsar Alexis. Like her younger sisters, she received an occidental education: the study of German and French languages, dancing and etiquette. Her teachers were Johann-Dietrich Christopher Osterman (brother of the future Vice-Chancellor) and Frenchman Etienne Rambur. Of Ivan V's daughters, she seems to have been the most capable. In 1708 the family moved to the new capital, Saint Petersburg.

According to contemporaries, Catherine was a short, dark-haired, and pale beauty and was a popular socialite with her charm and sociability.

At the request of her uncle Peter I, she was married on 19 April 1716 in Danzig to Karl Leopold, Duke of Mecklenburg-Schwerin. He had initially proposed to Catherine's sister Anna (then Dowager Duchess of Courland) but Peter I instead chose Catherine to be his bride. The marriage created a political alliance between Russia and Mecklenburg against Sweden, and was advantageous to Peter, as he wanted to use the port of Mecklenburg to harbour his fleet. According to the marriage contract, the Duke agreed to his future wife keeping her Orthodox faith, and to pay her 6,000 thalers per year. Peter I would, in return, contribute to the Duke's attempts to conquer the town of Wismar. They had two daughters: Elisabeth Catherine Christine (born in on 18 December 1718), and one unnamed (who was either stillborn or died immediately after birth on 18 January 1722).

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