Brosnan has married twice, having been widowed once, and has five children and three grandchildren. He met Australian actress Cassandra Harris through her stepson David Harris, the nephew of Richard Harris, shortly after leaving drama school. On meeting her, he said, "What a beautiful looking woman. I never for an instant thought she was someone I'd spend 17 years of my life with. I didn't think of wooing her, or attempting to woo her; I just wanted to enjoy her beauty and who she was." They began dating and bought a house in Wimbledon. They married in December 1980 and had one son together, Sean, who was born on 13 September 1983 and later became an actor. They also lived with Harris' children, Charlotte (1971–2013) and Chris, and Brosnan adopted them after their father Dermot Harris died in 1986; they subsequently took on his surname. Early in their relationship, Brosnan worked in West End plays and television films. After Harris appeared in the James Bond film For Your Eyes Only in 1981, they secured a bank loan and moved to Southern California, where Brosnan was cast in the title role of the TV series Remington Steele, easing their financial worries.
An episode of Remington Steele that was filmed in Ireland generated significant publicity. This led to Brosnan meeting his father, who had left when Brosnan was an infant, at his hotel. He expected to see a "very tall man" but instead described his father as "a man of medium stature, pushed-back silver hair, flinty eyes, and a twizzled jaw" who "had a very strong Kerry accent". He was regretful that they met under such public circumstances and wished for a more private arrangement.
While filming The Deceivers in Rajasthan in 1987, Harris became seriously ill. She was later diagnosed with ovarian cancer and died on 28 December 1991 at age 43. Brosnan struggled to cope with her death: "When your partner gets cancer, then life changes. Your timetable and reference for your normal routines and the way you view life, all this changes. Because you're dealing with death. You're dealing with the possibility of death and dying. And it was that way through the chemotherapy, through the first-look operation, the second look, the third look, the fourth look, the fifth look. Cassie was very positive about life. I mean, she had the most amazing energy and outlook on life. It was and is a terrible loss, and I see it reflected, from time to time, in my children." Harris had always wanted Brosnan to play James Bond; in 1995, four years after her death, Brosnan secured the role. His adopted daughter Charlotte also died of ovarian cancer, on 28 June 2013.In 1994, Brosnan met American journalist Keely Shaye Smith in Mexico. They were married in 2001 at Ballintubber Abbey in Ireland. They have two sons together named Dylan and Paris. They reside primarily in Malibu, California, with a second American home in Hawaii and Irish residences in Dublin and County Meath. On 11 February 2015, the $18 million Malibu home caught fire and sustained $1 million in damages. During the 30 minutes it took firefighters to extinguish the fire, flames destroyed the contents of the garage, including Brosnan's 2002 Aston Martin V12 Vanquish, and spread to a bedroom above it; no injuries were sustained.In July 2003, Queen Elizabeth II made Brosnan an honorary Officer of the Order of the British Empire for his "outstanding contribution to the British film industry". As an Irish citizen, he is ineligible to receive the full OBE honour, which is awarded only to a citizen of the Commonwealth realms, but he is still allowed the letters "OBE" after his name. In 2002, he was also awarded an honorary degree from the Dublin Institute of Technology and, a year later, the University College Cork. On 23 September 2004, he became an American citizen while retaining his Irish citizenship. He said, "My Irishness is in everything I do. It's the spirit of who I am, as a man, an actor, a father. It's where I come from." When asked by a fan if it annoyed him when people confused his nationality because of his fairly neutral accent, he said, "It amuses me in some respects that they should confuse me with an Englishman when I'm a dyed-in-the-wool, born and bred Irishman... I don't necessarily fly under any flag, but no, it doesn't bother me."
Brosnan has expressed contempt for his Christian Brothers education, but commented in 2013, "It always helps to have a bit of prayer in your back pocket. At the end of the day, you have to have something and for me that is God, Jesus, my Catholic upbringing, my faith... God has been good to me. My faith has been good to me in the moments of deepest suffering, doubt and fear. It is a constant, the language of prayer. I might not have got my sums right from the Christian Brothers or might not have got the greatest learning of literature from them, but I certainly got a strapping amount of faith." He attends Mass but also adheres to other spiritual beliefs, stating in 2008 that he loves "the teachings of Buddhist philosophy", which he referred to as his "own private faith". He elaborated, "I don't preach it, but it's a faith that is a comfort to me when the night is long."