Nina Weniger was born on 1 December 1968 in Frankfurt am Main as the daughter of the actors Monika Hessenberg and Wolfram Weniger. Already in primary school, she took part in radio plays and stood on stage in theatre productions. She began her studies at the Hochschule für Musik und Theater Hannover in 1989 and graduated in 1993. She then worked as a theatre director at the Kampnagel-Fabrik in Hamburg, the Schauspielhaus in Hamburg, the Schauspielhaus in Zurich and the Schaubühne in Berlin.    

Weniger's first television role was in an episode of the series "Unser Lehrer Doktor Specht" (1992). In the following years she appeared in several other series and television productions. She played one of the main characters in the lesbian coming-out story "Kommt Mausi raus? (1994, directed by Angelina Maccarone and Alexander Scherer) and took on recurring roles in the series "Bruder Esel" (1996), "Alarm für Cobra 11 - Die Autobahnpolizei" (1997) and "Zwei Männer am Herd" (1999).    

Nina Weniger made her debut on the big screen with a leading role as the main character's best friend in Angela Schanelec's "Mein langsames Leben" ("Passing Summer", 2001). In 2002 she trained as a yoga teacher. In 2003 she belonged to the ensemble of Stefan Krohmer's "Sie haben Knut" ("They've Got Knut").    

Mainly, however, Nina Weniger was seen in feel-good TV films such as "Tausendmal berührt" (2004), "Bettgeflüster & Babyglück" ("Baby You're Mine", 2005) and "Drei teuflisch starke Frauen" (2007), as well as in series such as "Hallo Robbie! (2005-2006) and "Notruf Hafenkante" (2009). She has also appeared in around 50 radio play productions for various radio stations.   

In 2009, Nina Weniger embarked on a second career: she began studying Scandinavian Studies and European Ethnology in Berlin, graduating in 2014. During this time she gave up acting. During her studies she spent a year in Stockholm, where she studied rhetoric and Nordic languages. Since 2012 she has been teaching practical rhetoric in Scandinavian languages at the Northern Europe Institute of the Humboldt University in Berlin.   

After graduating from university, Weniger resumed acting in 2015 and took on a recurring role in 47 episodes of the daily soap "Rote Rosen", playing the entrepreneur's wife Jeanette Drechsler. She then guest starred in individual episodes of "Alles Klara" (2016), the Netflix series "Dark" (2017) and in "Familie Dr. Kleist" (2018). 

Weniger played her first leading role in Katharina Wackernagel's feature film directorial debut "Wenn Fliegen träumen" ("When Flies Are Dreaming", 2018), as a woman at risk of suicide who embarks on an eventful journey to Norway with her half-sister. The film celebrated its premiere at the Hofer Filmtage 2018 and was released in German cinemas in the summer of 2018.