Cornelia Grünberg was born on December 23, 1959, in Berlin. From 1987 to 1994, she studied directing and screenwriting at the German Film and Television Academy Berlin (dffb). Her feature-length graduation film "Paul IV" (1995), based on Andreas Steinhöfel's novel "Paul Vier und die Schröders," premiered at the Gera Children's Film Festival Goldener Spatz, where it received both the Special Jury Prize and the MDR Broadcasting Council Award.

In 1999, her children's adventure film "Zwei in einem Boot" ("Two In A Boat") screened in the Berlinale's children's film competition and won the First Jury Prize at the Festival of Eastern European Film in Cottbus. That same year, her 20-minute youth film "First Kiss" premiered at the Children's Film Festival Goldener Spatz.  

From 2001 to 2014, Cornelia Grünberg taught Camera Acting and Film History at the Berlin Acting School for Film. During this time, she also directed episodes of the TV series "Unsere Zehn Gebote" (2005) and "KI.KA-Krimi.de" (2007).  

In 2008, Grünberg began her long-term documentary project "14-18-28," a trilogy following four girls who became pregnant at 14 and chose to keep their babies. The first film, "Vierzehn – Erwachsen in 9 Monaten" ("14 – Grown up in 9 Months," 2008), which follows the teenagers through pregnancy and birth, premiered in the Berlinale Generation 14plus competition in 2012. The second installment, "Achtzehn – Wagnis Leben" ("18 - Dare to Live," 2012), was released in cinemas in October 2014. At the 2015 Ökofilmtour festival in Potsdam, Grünberg received the award for Best Artistic Achievement, and she was nominated for the Metropolis Directing Award by the German Directors' Association.

Filming for the final part of the trilogy took place in 2023. "Achtundzwanzig – Der Weg entsteht im Gehen" ("Twenty-Eight – The Path is Made by Walking") portrays the mothers as adult women whose children are now 14 years old – the same age they were when they gave birth. The film is set for theatrical release in October 2025.  

From 2018 to 2024, Cornelia Grünberg served on the board of the German Directors Association (BvR), and from 2019 to 2020 she was part of its executive committee. In 2022, she joined both the Administrative Board and the Executive Committee of the German Federal Film Board (FFA).