Gummer was nominated for the 2016 Drama Desk Award for Outstanding Actress in a Play for the original production of Ugly Lies the Bone.

[6] After graduating from college in 2005, she made her off-Broadway debut alongside Michael C. Hall in the premiere of Noah Haidle's Mr. Marmalade, for which she won a Theatre World Award.

Gummer made her motion-picture debut as an adult with a minor role in Lasse Hallström's The Hoax (2006), starring Richard Gere.

[8] She also guest-starred on the CBS legal drama The Good Wife in the season 1 episode "Bad" portraying Nancy Crozier.

In April 2011, she starred with Hamish Linklater and Alison Fraser in the Off-Broadway production of The School For Lies written by David Ives, directed by Walter Bobbie, and produced by Classic Stage Company.

[12] Gummer played Lucy Purcell, a mother of two children who finds herself involved in a crime, in the third season of HBO's anthology drama True Detective.

[14][15] They married in July 2011 at her parents' home in Connecticut,[16] and resided in Park Slope, Brooklyn, New York City.