After completing her junior year at the university, she interned at Mad Magazine in New York City. Ganz had planned to move back to Michigan after her internship was over, but Mads editor-in-chiefJohn Ficarra encouraged her to remain in New York and pursue comedy writing. She returned to New York and became assistant editor at The Onion and was later promoted to associate editor.
In 2010, she began writing for the NBC comedy series Community. In 2013, after the shortened season 4 of Community had wrapped, Ganz joined the writing staff of the ABC series Modern Family. In 2015, Ganz created and produced an animated action-comedy pilot called Cassius and Clay which was expected to be paired with Archer on FXX, but the show never progressed beyond the pilot stage.
Ganz began dating British comedian Humphrey Ker in 2013. The couple were engaged in late 2014, and married on May 30, 2015.
In 2018, during a Twitter exchange with Community creator and executive producer Dan Harmon, Ganz accused Harmon of having engaged in inappropriate behavior toward her during their time on the show together. Harmon detailed his behavior on an episode of his podcast, Harmontown, in which he went into detail about his wrongdoings which included making advances on her and then mistreating her after she turned him down. Ganz said that she felt vindicated by the admission and accepted his apology, urging her Twitter followers to listen to this episode of Harmontown, and calling it a "master class in how to apologize", ultimately forgiving him. The exchange, the apology and Ganz's thoughts about them were covered in episode 674 of This American Life in which she was interviewed.
The following is a partial list of television episodes written by Ganz.