Starr is a graduate of the California State University, Northridge where she earned a degree in Journalism. From 1979 to 1988 she was a correspondent for Business Week magazine covering energy matters. She then worked for the news magazine Jane's Defense Weekly from 1988 to 1997 covering national security and defense policy, before joining ABC News as a producer covering the Pentagon, where she won a local Emmy Award.
In June 2013, MSNBC reporter Chris Hayes ran a segment in which he argued that Starr's publication of leaked information was at least as potentially harmful to national security as those published by Glenn Greenwald of The Guardian. He noted the fact that, unlike with Greenwald, politicians and other prominent figures failed to call for Starr's prosecution on the basis that Starr's use of leaked information invariably favoured government interests, implicitly questioning Starr's independence and arguably even her integrity and status as a journalist.
In July 2015, Starr received criticism from Kenyans through a twitter hashtag that trended for several hours on Internet when she called Kenya a 'terror hot bed' as Obama headed to the East African nation. She was referring to the security threat posed by Alshabaab militants operating in neighbouring Somalia.