[citation needed] DeFer made her acting debut in a March 2004 episode of the Nickelodeon sitcom Drake & Josh.

She has since made a number of guest appearances on television shows such as Quintuplets, Ghost Whisperer, CSI: Miami, and How I Met Your Mother.

In April 2011, The CW announced DeFer would have a major recurring arc in both the fourth and fifth seasons of Gossip Girl.

DeFer portrayed the role of Ivy Dickens, a con artist who pretends to be Charlotte "Charlie" Rhodes in order to get access to the latter's trust fund.

She reprised her role of Ivy in the series' sixth and final season and was listed as a main cast member.

[3][4] DeFer subsequently began dating Michael Fitzpatrick, lead vocalist for the band Fitz and the Tantrums, and in May 2013, she announced that they were expecting a child together.