Count Ivan Illarionovich Vorontsov (1719, 1786) held positions as a senator, actual chamberlain, and president of the Estate Collegium in Moscow. He was the brother of Chancellor Mikhail Illarionovich Vorontsov and General-Field Marshal Roman Illarionovich Vorontsov, as well as the uncle of Princess Ekaterina Romanovna Dashkova. Ivan was married to the daughter of the famous cabinet minister Artemy Volynsky, who was executed during the reign of Anna Ioannovna.

Ivan was the youngest son of Illarion Gavrilovich Vorontsov and Anna Grigoryevna Maslova. In November 1741, his elder brother Mikhail participated in the palace coup in favor of Elizabeth, the daughter of Peter the Great. This coup significantly elevated the Vorontsov brothers. Soon, Mikhail became the state chancellor, Roman the general-field marshal, and Ivan received the rank of lieutenant in the Preobrazhensky Life Guards Regiment.

Empress Elizabeth married Ivan Illarionovich to her second cousin Maria Volynskaya, who was returned from a convent. Maria was the daughter of cabinet minister Artemy Volynsky and Alexandra Lvovna Naryshkina, the niece of Empress Natalia Kirillovna and a cousin of Peter the Great. Volynsky was executed in 1740.

This marriage brought Vorontsov a significant dowry and kinship with the royal family. On the day of the wedding, the empress returned the ancestral estate of the Volynskys, Voronovo, to the newlyweds.

In 1753, Ivan Vorontsov received the rank of captain in the Preobrazhensky Regiment, and two years later became a chamber junker to Grand Duke Peter Fyodorovich. In 1760, at the request of the empress, he was elevated to the rank of count of the Holy Roman Empire. Upon ascending the throne, Peter III granted Ivan the rank of general-poruchik. When Catherine II ascended the throne, Ivan Vorontsov, taking advantage of the manifesto on the freedom of the nobility, submitted his resignation.

After retiring, Ivan Illarionovich settled with his family in Voronovo, where he focused on arranging the estate. According to the project of architect Karl Blank, a manor house, the Spasskaya Church in the Baroque style, and the Dutch House, built in the style of the bourgeois houses of the 16th century, which were very popular at that time, were constructed. In 1775, Catherine II, returning from Kashira, visited the Voronovo estate. In memory of this visit, stone obelisks were erected on the main alley of the park behind the pond.

Ivan Illarionovich Vorontsov passed away in 1786 and was buried at the Voronovo estate.