Pomeranz was born Margeret Anne Jones-Owen in Waverley, a suburb of Sydney. She was educated at the Presbyterian Ladies' College, Sydney in Croydon, the then newly opened Macquarie University, where she graduated with a Bachelor of Arts degree in German and psychology, and the Playwright's Studio at the National Institute of Dramatic Art (NIDA).
She joined the Special Broadcasting Service (SBS) in 1980 as writer/producer, and was appointed producer for David Stratton's film presentations.
Together with Stratton, she hosted the long-running SBS TV program The Movie Show from 1986 until 2004. She appeared on the Australian Broadcasting Corporation (ABC) version of the program, At the Movies, again with David Stratton, beginning in 2004 and concluding on 9 December 2014.
She also had an uncredited role in the 1994 film The Adventures of Priscilla, Queen of the Desert as Adam's mother.
In addition to being a critic, Pomeranz is also an anti-censorship campaigner. She was a prominent attendee and was briefly detained by police at an attempted 2003 protest screening of the controversial film Ken Park, banned in Australia. She has been critical of the Australian Office of Film and Literature Classification (now the Australian Classification Board), the Australian censorship body, on a number of occasions. She has actively spoken out against production companies refusing to give preview screenings for critics.
Pomeranz has often said that her favourite films are Robert Altman's Nashville and David Lynch's Blue Velvet.
She is prominently noted for the large earrings she wore on the show, apparently designed by a friend.
Pomeranz was made a Member of the Order of Australia in the 2005 Australia Day Honours.
On 29 January 2015, it was announced that Pomeranz had signed with Foxtel to present film and television programs.
Pomeranz has appeared as herself in several Australian comedy programs.
In 2009's Lawrence Leung's Choose Your Own Adventure she and David Stratton review Lawrence Leung's attempt to set a world record for solving the Rubik's Cube whilst sky diving, as they sit on the landing site in their trademark armchairs.
In a 2010 video promoting the new Triple J breakfast team of Tom Ballard and Alex Dyson, she joined the two men to "satisfy the female demographic".
Pomeranz also appeared as herself in:a 2000 episode of Australian comedy show Pizza, a show known for celebrity cameos
Australian sketch comedy show Full Frontal in a 1995 episode
1993 Australian comedy film Hercules Returns