Neeson was ranked among both the "100 Sexiest Stars in Film History" and "The Top 100 Movie Stars of All Time” by the Empire magazine.

Neeson lived with his girlfriend and actress Helen Mirren during the early 1980s. They had met on sets of Excalibur (1981) while working together. Interviewed by James Lipton for Inside The Actor's Studio, Neeson said Mirren helped him in getting an agent. Neeson met his future wife, actress Natasha Richardson, while performing in a revival of the play Anna Christieon Broadway, in 1993. They married on 3 July, 1994. In August 2004, Neeson and his wife purchased an estate in Millbrook, New York. He first worked with his future wife and actress Natasha Richardson on the miniseries Ellis Island, in 1984.

Their marriage was going well till on 18th March 2009, Richardson died when she suffered a severe head injury in a skiing accident at the Mont Tremblant resort, north of Montreal. Liam was lost for words, for many days after her demise. She and Neeson had two sons together, Micheál (born 1995) and Daniel (born 1996). Although he never had a divorce in his life, yet he had an affair with Brooke Shields, Julia Roberts and Janice Dickinson before his married life. In October 1998, he won a case against a newspaper, which claimed that his marriage was in trouble.

A heavy smoker earlier in his career, Neeson quit smoking in 2003, while working on Love Actually. When he took the role of Hannibal for the 2010 film adaption of The A-Team, Neeson had reservations about smoking cigars (which is a signature trait of the character) in the film due to being an ex-smoker, but agreed to keep that personality trait of Hannibal intact for the film. In March 2011, he was appointed a Goodwill Ambassador for UNICEF. Having a networth of $75 million, he is one of the richest actors in Hollywood.

He has expressed his affection for the Adhan, the Islamic call to prayer that he developed while shooting for Taken 2 in Istanbul. He has also expressed admiration for the Spiritual Exercises of Saint Ignatius of Loyola.

Neeson loves fly fishing. He was a boxer as a teenager in Northern Ireland, which resulted in getting his nose broken, at the age of 15. A brief blackout after one of his fights caused him to give up the ring for good. He is a very energetic and active person and that has helped him a lot in his career.