Harrison died at 1:30 p.m. PT on Thursday in Los Angeles, following a battle with a brain tumor that ultimately caused his demise. His wife, Olivia, and 24-year-old son, Dhani, were with Harrison at the time of his death.
"He left this world as he lived in it, conscious of God, fearless of death, and at peace, surrounded by family and friends,'' the Harrison family said in a statement to reporters. "He often said, 'Everything else can wait but the search for God cannot wait, and love one another.'"
"I am devastated and very, very sad. He was a lovely guy and a very brave man and had a wonderful sense of humor. He is really just my baby brother," McCartney said.
Buckingham Palace said Queen Elizabeth was "very sad to hear the death of George Harrison," AP reports.
Great Britain's Prime Minister, Tony Blair, also expressed his sentiments to BBC News on Thursday. "He wasn't just a musician, an artist, but did a lot of work for charity as well. He'll be greatly missed around the world."
"George Harrison was once of the great Liverpudlians," Liverpool's Lord Mayor Gerry Scott told Reuters. "He was a warm, peace-loving man who much more than just a talented musician."
"I would say he was the major cog in the Beatles at that time. He kept them together probably because of the calming effect he had," Williams said.
Harrison was 13 years old when he bought his first guitar and befriended Paul McCartney at school. McCartney introduced him to John Lennon, who was in a band called the Quarrymen. After several lineup changes and a name change, McCartney, Lennon and Harrison brought drummer Ringo Starr aboard and the Beatles were born.
During the same year, he organized the Concert for Bangladesh, one of the first rock 'n' roll benefits, and helped fellow musician Sir Bob Geldof put together Live Aid, a benefit for African famine in 1985, AP reports.
"It really is the end of a dream," John Chambers of the Liverpool Beatles Appreciation Society told AP. "The only comfort we can take is the legacy of the music, which is as powerful and mysterious today as it ever was."
Fans across the globe are mourning Harrison's death.
At Harrison's mansion outside of London, fans have left flowers and notes for the guitarist. Flags were flying at half mast and a book of condolence has been opened at Liverpool Town Hall, birthplace of The Beatles, BBC News reports
In addition, the city council has announced that there will be a memorial service for Harrison, but no date has been set.
Harrison was also awarded the freedom of the city in 1984, Reuters reports.
"The thing that pleases me the most about it is that young people like it," Harrison said in an interview with AP at the time. "I think the popular music has gone truly weird. It's either cutesy-wutesy or it's hard, nasty stuff. It's good that this has life again with the youth."
On Oct. 1, Harrison recorded the song "A Horse To Water" with his son Dhani and pianist Jools Holland at his Switzerland home. The tune is featured on Holland's album Small World, Big Friends, released on Nov. 19 in the UK.
In New York City, fans began gathering before dawn Friday at Strawberry Fields, a section of the city's Central Park created in memory of another fallen Beatle, John Lennon, who was killed outside his nearby apartment in 1980.
Harrison spent last week at New York's Staten Island University Hospital where he was treated for his cancer. After his release on Nov. 22, Harrison took a private jet to Los Angeles, where he was treated with conventional chemotherapy at the UCLA Medical Centre, ABCNEWS.com reports.
"When I saw him last time, he was obviously very unwell but he was cracking jokes like he always has...he'll be sorely missed," McCartney told AP.
The singer waged a long battle with cancer during the last few years.
In May, Harrison underwent surgery at the Mayo Clinic in Rochester, Minn., to remove a cancerous growth from one of his lungs. In April, a malignant growth was taken from one of his lungs.
Harrison was treated for throat cancer after doctors found a lump on his neck in 1997.
"It reminds you that anything can happen," he said at the time. Harrison blamed years of smoking cigarettes for his illness.
Harrison received courses of radiation therapy at Britain's leading cancer treatment center, the Royal Marsden Hospital, at that time.
Harrison is survived by his wife and son, his brother, Peter, and his sister, Lou.