Catinca was born in Bucharest, Romania on 21 March 1997, the only child of Untaru family. When she was three years old, she told her grandparents that she would like to became a theatre actress waiting for people to give her flowers on a stage. From an early age, she was fascinated by fantasy stories and legends. She started to take English lessons at the age of 4 and her teacher, a former Romanian flight attendant, noticed her interest and started to tell her stories about countries and customs to keep her focused. Soon she was speaking English with different accents. She competed against hundreds of children from all over the world for the role of Alexandria, the main character in Tarsem Singh's The Fall (2006). She won the role, despite not fitting the initial character description. Catinca Untaru became the first Romanian child actress to star in an international film. Right from the start, her discovery has consisted of a series of fortunate coincidences.

At first, it was the recommendation of one of her former teachers that lead talent agent Andreea Tanasescu to her. Then, an incredible audition with Tarsem Singh, the director of The Cell (2000), during which Catinca managed to switch back and forth between reality and fantasy without the slightest degree of effort. Catinca managed to convince Tarsem that she was the right child for the part of Alexandria. With quite a serious face for a 10 year old, Untaru says that she enjoyed filming for "the Fall" and that her favorite part of the whole experience have been the costumes designed by Academy Award winner Eiko Ishioka. The entire script was never revealed to Catinca, as she started shooting for "The Fall"(2006) she was constantly kept on her toes about the story. She thus managed to become an active part of the action. Catinca's mother Ruxandra recalls that she would be Catinca in her hotel apartment but would immediately switch to Alexandria when she was the set.

Catinca says that being a part of the cast of The Fall allowed her to see countries and learn about customs. As the shooting took place in more than 20 locations around the world, Catinca was most impressed with India. Although quite mature for her age, Catinca still enjoys playing with her dolls and, most of all her friends. When she was filming for "The Fall"(2006), her biggest wish was to come back home and be able to play with her friends whom she was missing dearly. She likes to read books, to write stories and maybe to do movies in one day. Now, almost 3 years after filming ended, Catinca goes to school and is head of class. As of January 2007, she was working in a Romanian experimental media project called "10" where a group of kids are planning to do a movie. It is a mix of reality and fantasy production inspired from her story.