A drug overdose is suspected in her death, the Irish Independent reported.
Price, 62, was found unconscious on her bed about 10 p.m. Wednesday by her son, officials said.
She was believed to have suffered from post-traumatic stress disorder. Police said Price had overdosed on drugs previously.
She was convicted of involvement in the bombing of London's Old Bailey in 1973 in which more than 200 people were injured.
Price was released from prison and married Rea in 1983, with whom she had two sons. Price and Rea divorced in 2003.