She has appeared in ad campaigns for Ralph Lauren, Versace, Chanel, and Giorgio Armani. She also posed topless for the February 2007 issue of Playboy. Helfer appeared as Chuck’s Season 2 secret agent “handler” in the NBC series Chuck, and as Michael Westen’s Season 2 nemesis in the USA Network series Burn Notice as “Carla.” Helfer appears as herself in Old 97′s music video for “Dance with Me”. She guest starred in “Resonance,” the second episode of Warehouse 13 as FBI Agent Bonnie Belski on Syfy. She has played several prominent video game roles in recent years; including Kilian Quatar in Command & Conquer 3: Tiberium Wars, Veronica Dare in Halo 3: ODST and EDI, the ship-borne artificial intelligence aboard the Normandy SR-2 in Mass Effect 2. She also voices Sarah Kerrigan in StarCraft II: Wings of Liberty, as well as its expansion sets, Heart of the Swarm and Legacy of the Void. Helfer has joined the cast of Jerry Bruckheimer’s TNT drama, Dark Blue as FBI Special Agent Alex Rice.

Helfer has walked for top fashion shows such as Carolina Herrera, Christian Dior, Claude Montana, Givenchy, John Galliano, and Dolce & Gabbana. She relocated to Los Angeles in 2002 to pursue a full-time film career. Thereafter, she played the role of a model, Ashleigh James, in the May 16, 2002 episode “The Hunger Artist” on CSI: Crime Scene Investigation.

She has been actively involved in different charity events, from animal rescue to the oil spill in the Gulf. She has appeared in ad campaigns for Ralph Lauren, Versace, Chanel, and Giorgio Armani. She also posed topless for the February 2007 issue of Playboy. Her first acting assignment was a co-starring role as Sarah on the television series Jeremiah. in 2004, Helfer played Farrah Fawcett in the NBC telemovie The Unauthorized Story of ‘Charlie’s Angels’.