"We have lost a national treasure," said Irish Prime Minister Enda Kenny.
It was the first of many best-sellers by Binchy, who joked that she could write as fast as she could talk. Although her novels were marketed as romances, many reviewers said her realistic and complicated approach to storytelling made them transcend the category.
Her 18th novel, "A Week in Winter," is scheduled to be published later this year.
The depiction of human relationships and their resulting crises was a familiar theme for Binchy, and she addressed them in two of her better-known books, "Circle of Friends" (1990) and "Tara Road" (1999). Both were made into films, as was a short story, "How About You."
"A hallmark of a Binchy book is a cast of characters Dickens would relish," Mary McNamara wrote in The Times in 1999, "all pairing and sundering, congregating and dispersing in an operatic minuet. Plots and subplots surface and submerge" in a story that invariably ends in "acceptance and growth."
Binchy considered herself a writer of escapist works popular with people going on vacation.
"I was just lucky," she told the BookReporter website, "I lived in this time of mass-market paperbacks."
The eldest of four children, she was born May 28, 1940, in Dalkey, a village outside Dublin, to attorney William Binchy and his wife, Maureen, a nurse.
After a childhood in Dalkey that she always described as happy, Binchy graduated from University College in Dublin in 1960 and went into teaching.
At 23, she visited an Israeli kibbutz and wrote letters home describing the experience. She returned to discover her father had persuaded the Irish Times to publish them.
She taught until 1968 and then joined the Irish Times as women's editor before moving to England in the early 1970s as the paper's London correspondent.
Just when she was thinking "it was a bit too late," she told The Times in 1999, she met broadcaster Gordon Snell and married him, in 1977. He is also a children's author.
The couple soon moved to the village where she grew up. She had already written her first play, "End Term," and increasingly turned toward novels. She continued writing for the Irish Times until 2000.
Two of her novels were made into TV productions: "Echoes," about life in a small Irish town, was a 1988 miniseries, and "The Lilac Bus," about characters on a bus headed to Dublin, was turned into a 1990 television movie.
In 2000, she announced that the 560-page "Scarlet Feather" would be her last novel but later said she was retiring from writing "big, major novels" that required promotional tours. Binchy made millions a year and said she wanted to slow down to enjoy her wealth.
Another novel, "Quentins" appeared in 2002, the year she was hospitalized with a serious heart condition. The rhythms of the hospital inspired another Binchy novel, "Heart and Soul" (2009).
Her books reflected the positivity with which she lived her life.
"I don't think you're happier if you're thin or beautiful or rich or married. You have to make your own happiness," Binchy toldAustralia'sIllawarra Mercury newspaper in 2000. "My heroines do not become beautiful elegant swans, they become confident ducks and get on with life."
In addition to her husband, Binchy is survived by her brother, William, and her sister, Joan.