Patricia Breslin was born in New York City, one of three children born to Edward (a judge) and Marjorie Breslin. Her father was a Catholic of Irish descent and her mother was of Scottishdescent. She graduated from the Academy of Mount St. Ursula High School and the College of New Rochelle.
In 1954, she guest-starred with Peter Mark Richman in an episode of NBC's legal drama, Justice, as a woman threatened by hoodlums.In 1955, Breslin was cast in an episode of the CBSanthology series Appointment with Adventure, a series with neither a host nor a regular star.
Between 1960-1963 Breslin made three guest appearances on CBS's Perry Mason, and was cast as the defendant in all three episodes. In 1960 she played Karen Lewis in "The Case of the Lavender Lipstick." In 1962 she played Karen Ross in "The Case of the Poison Pen-Pal," and in 1963 as Laura Hewes in "The Case of the Prankish Professor."
In 1960, she played the newlywed wife of William Shatner's character in CBS's The Twilight Zone episode "Nick of Time" and also in the 1963 Twilight Zone episode "No Time Like the Past", in which she portrayed Abigail Sloan.
In 1960, she guest starred on the short-lived David McLean western series, Tate, which aired on NBC. She appeared on Nick Adams' ABC western, The Rebel and with Jack Lord in his ABC adventure series, Stoney Burke. Thereafter, Breslin played the role of Anne Mitchell, along with co-stars Ralph Bellamy and Paul Fix, in the 1961 episode "The Haven" of CBS's anthology series, The DuPont Show with June Allyson.
Breslin married former Cleveland Browns and Baltimore Ravens NFL team owner and advertising and business executive Art Modell in 1969. Breslin had two sons from her first marriage to character actor David Orrick McDearmon (1914–1979), sons John and David. Shortly after their marriage, Modell legally adopted Patricia's sons and they took his surname. The family lived in Owings Mills, Maryland with a total of six grandchildren between them.
Breslin died on October 12, 2011, at the age of eighty after a lengthy hospitalization with pancreatitis. Her funeral was offered at the Basilica of the National Shrine of the Assumption of the Blessed Virgin Mary in Baltimore, Maryland. Her husband, Art Modell had been a major contributor to the restoration of the basilica.Breslin died five months after the passing of her The People's Choice co-star, Jackie Cooper.