Born in Stillwater, Minnesota, Abercrombie started his career at the Fargo Forum and the Milwaukee Journal. His innovative and stunning photographs quickly drew attention and acclaim. By designing an underwater housing (commercially unavailable at the time), Abercrombie pushed the frontiers of photography when he photographed a shipwreck at the bottom of Lake Michigan. Surreal portraits of wife, Lynn Abercrombie, distorted by reflections in stainless steel cook and house ware were published in Life Magazine. His photograph of a robin straining to extract an earthworm from a dramatically low angle caught the eye of Melville Bell Grosvenor at the National Geographic.

He was invited to work at National Geographic, where his first report was from Lebanon. He had never been abroad before.

As a staff member of National Geographic, Abercrombie was best known for his work in Arab countries, visited all seven continents, and was one of the first two journalists to reach the South Pole in 1957 (the other was Rolla J. "Bud" Crick of the Oregon Journal). Abercrombie was the first person to win both the Newspaper Photographer of the year (1954) and the magazine photographer of the year (1959). He dived with Jacques Cousteau who said it "was like swimming with a fish".

After 1965 Abercrombie frequently covered Saudi Arabia and he converted to the Muslim faith, taking the name Omar. He was the magazine's expert on the Middle East, and reported from Mecca. He covered the region from Morocco to Afghanistan for more than three decades, until he retired in 1994. During his forty years at National Geographic, he published forty stories from all around the world.

After retiring from National Geographic in 1993, Abercrombie taught geography at George Washington University. He was fluent in five languages (Arabic, English, German, French, and Spanish), but could swear in many more.

Abercrombie died at Johns Hopkins Hospital, Baltimore, Maryland of complications from open-heart surgery. He was survived by his wife, Lynn, and children Mari, executive director of Windover Art Center, and Bruce, a videographer.

Abercrombie's photojournalism career is documented in the 2004 film, White Tiger: The Adventures of Thomas J. Abercrombie, by filmmaker Patricia A. Leone, Blue Marlin Productions, Progressive IMG and Gabriel Film Group with original music score by Kevin Harkins. The film showed at the New York International Independent Film and Video Festival.

The August 2006 issue of National Geographic included an Abercrombie tribute article, "A Geographic Life" . In addition, the Abercrombie Crests of Antarctica are named in his honor.

Abercrombie is also one of four pioneering photographers to be honored in Odysseys and Photographs book published by the National Geographic Society, along with an exhibition at the National Geographic Museum in Washington, D.C. and in London.