Helena Christensen stepped into the limelight in 1986 by claiming the title of Miss Denmark at age 18, and representing her country at the Miss Universe pageant. She left her home soon afterwards to pursue modeling in Paris.

Christensen is considered to be one of the more prominent supermodels of the 1990s, having appeared on many magazine covers and in fashion campaigns. She was in the Victoria's Secret catalog and in their television commercials as one of the signature Angels, along with supermodels Tyra Banks Karen Mulder, Daniela Pestova Rebecca Romijn, and Stephanie Seymour

In 1991, she starred in the music video for Chris Isaak's song "Wicked Game". In the video, she is depicted as Isaak's lover. Christensen and Isaak were both topless for much of the video, though her nudity is relatively concealed. It was decided that full frontal nudity would not be suitable for mainstream release. Viewers still reacted to Christensen's sexually suggestive performance, and the video was later featured on MTV's "Sexiest Video of All-Time". This video was voted #4 on VH1's "50 Sexiest Video Moments" and voted #13 on VH1's "100 Greatest Videos".

Christensen is signed to Independent Models in London and 1/One Management in New York City, 2pm Model Management in Copenhagen.

She has an antiques shop in Manhattan and sells some of her clothes in her mother's Yo-Yo Second Hand Shop in Christianshavn.

She co-founded Nylon magazine as the original creative director with American entrepreneur Mic Neumann. She has launched her own clothing line Christensen & Sigersen, with long-term friend Leif Sigersen. The pair also runs Butik, a shop in New York.

Christensen is also a photographer, and her photos appeared in magazines such as Marie Claire and ELLE. Her exhibition, A Quiet Story, premiered in Rotterdam in 2006.

Christensen lived with Inxsfrontman Michael Hutchence and has been romantically linked to Leonardo DiCaprio. She has one child, a son named Mingus Luchien Reedus, with actor Norman Reedus Reedus and Christensen split in 2003. From 2004 to 2006, Christensen dated Danish rock band Grand Avenue frontman Rasmus Walter-Hansen. Christensen is currently dating Interpol frontman Paul Banks.