Kateřina Janečková was born on 7 May 1983 in Šumperk. She comes from a family of artists. Her mother is an actress and her father is a film director. As a child, her dream was to dance, which was inspired by her grandmother Lea Janečková, a well-known choreographer. Under her guidance, Kateřina devoted herself to expressive dance, but later she also wanted to act as such. She applied to the conservatory. She first studied at the University of Prague and then at the University of Ostrava.
She gained her first real acting experience in front of the camera at the age of eleven. Along with Dagmar Veškrnová, she appeared in the series When the Sun Doesn't Work. Later, she began to appear more or less regularly on television screens - for example, the fairy tale Restaurant to the Prince , where she met Matěj Hádek, who played Prince Filip II, in the role of Princess Róza. She could also be seen in the series Trailier - Second League and Family Bond . However, her role as the devoted secretary Kateřina Bertoldová in the TV series Prima Osklivka Katka brought her real popularity.