Born in Estonian city of Reval (now Tallinn), Catherine was the third child and only daughter of Prince Peter August of Schleswig-Holstein-Sonderburg-Beck, who was a Russian field marshal and Governor of Estonia, and his second wife, Countess Natalia Nikolaievna Golovina (1724-1767).

On her father's side, Catherine belonged to the Beck branch of the Schleswig-Holstein-Sonderburg line of the House of Oldenburg being, in unbroken male-line, a descendant of King Frederick I of Denmark through his second son Johann II, Duke of Schleswig-Holstein-Haderslev and also she was distantly related to Emperor Peter III of Russia (born Charles Peter Ulrich of Schleswig-Holstein-Gottorp; he was a descendant of Johann II's younger brother Adolf, Duke of Holstein-Gottorp).

However, after his death, Empress Elizabeth of Russia disregarded the will and ordered to give the village of Khovrino (now Grachevka) near Moscow with the entire inheritance to Count Nikolai's only legitimate child with his wife, Sophie Pushkina (1700-1745), Countess Natalia Nikolaievna Golovina (1724-1767) (Catherine's mother).

[3]On the occasion of his wedding, Prince Baryatinsky received 4,000 serfs and villages in the Kursk province: Ivanovskoe [ru],[4] Snagost and others in the Rylsky District, which Emperor Peter I gave to Hetman Ivan Mazepa before his betrayal.

However, Prince Baryatinsky himself wasn't a faithful spouse, at the same time he had a relationship with the wife of the Imperial Chamberlain, the beautiful Countess Anastasia Nikolaevna Neledinskaya.

According to court gossip, Princess Baryatinskaya went to Paris pregnant from Count Razumovsky's child, where she gave birth, covering up her adventure with a seizure of "water illness".

French diplomat Baron Daniel de Corberon [ru], having met Princess Baryatinskaya in 1776, wrote in his diary: Outwardly, I liked her: extremely graceful, with an amazing waist, expressive features, dignified and relaxed in movements, but at the same time a little mannered.

[6]Officially separated from her husband but retaining her title, the frivolous beauty didn't receive invitations to the small court of Grand Duke Pavel Petrovich, which upset her very much.

In September 1774, Princess Baryatinskaya's father Peter August assumed the headship of the Beck line of the House of Schleswig-Holstein-Sonderburg after the death of his brother Duke Charles Louis without surviving male issue; however, he died five months later, on 24 February 1775.

Later, in his essay on Princess Baryatinskaya, Prince Ivan Mikhailovich Dolgorukov [ru] wrote: Her wealth, name, and even her more gentle character and amiable qualities of her heart attracted the entire selected city to her.

She lived luxuriously and pleasantly together, with everyone she was polite, supportive and approximately hospitable; being always at odds with her husband, she wanted to fill the theatrical society of her children with well-bred young people, among whom I was honored to be.

The purpose of the trip was treatment for an illness in Aix-la-Chapelle; she was accompanied by the Empress's physician Adam Weikart, her son Ivan (whom she intended to enroll in one of the German universities), and the young Countess Amalie Louise of Sayn-Wittgenstein-Ludwigsburg.

In this famous painting, Princess Baryatinskaya is depicted sitting in an armchair at the table on which there is a marble bust of her father work of the German sculptor Alexander Trippel [de].