Ekaterina Ivanovna Briner-Kornakova, the second wife of Boris Yulievich Briner, was born on June 10, 1895, in Kyakhta. Her father, merchant Ivan Iokinfovich Kornakov, assisted famous explorers in organizing expeditions, while her mother, Augusta Dmitrievna Sinitsina, was a folklorist and ethnographer awarded a medal by the Russian Geographical Society. The family initially lived in Kyakhta, then in Mongolia, where Kateryna's parents participated in amateur performances.

Kateryna's acting talent was revealed at the Yankovskys' estate, where she played Baba Yaga in the play "The Poet's Dream." In the mid-1910s, she studied at the Moscow Private Drama School and worked with K.S. Stanislavsky, becoming one of his favorite students. In 1916, she became an actress at the Moscow Art Theatre, debuting as Lida in Z. Gippius's play "The Green Ring." Among her other roles were Sashenka Rostaneva in "In the Village of Stepanchikovo" and Alina in "Balladine."

Kateryna was married to actor Alexei Diky, but their family life did not work out. In 1924, she met Boris Briner and left her husband and career for him, moving to Vladivostok. In Harbin, she recognized the acting talent in her stepson Yulia and gave him a recommendation letter to Mikhail Chekhov, which marked the beginning of his acting career in America.

In Harbin, Kateryna organized a dramatic arts studio and staged several performances. Unable to have children, in 1938 she and her husband adopted a girl named Katya. In 1945, the family was deported to the USSR, but thanks to Leonid Briner's efforts, they were exchanged for Soviet citizens in Switzerland. After her husband's death in 1948, Kateryna and her daughter moved to London, where she died of cancer on August 15, 1956. Her daughter's guardian became Yul Brynner, the famous Hollywood actor.