"She died peacefully, with family by her side,” according to the statement.
“Rosalynn was my equal partner in everything I ever accomplished,” Mr Carter said. "She gave me wise guidance and encouragement when I needed it.
"As long as Rosalynn was in the world, I always knew somebody loved and supported me.”
Throughout their 77 years of marriage, Ms Carter was considered one of her husband’s closest advisers and often hit the campaign trail alone.
Journalists called her the “steel magnolia”, as her quiet demeanour hid a “tough as nails” interior.
As first lady, she was known to sit in on cabinet meetings. She served abroad as a special envoy to Latin America and visited Thailand, Brazil, Costa Rica and Poland and even led the US delegation in Rome for the funeral of Pope Paul VI.
“I was there to be informed so that when I travelled across the country, which I did a great deal, and was questioned by the press and other individuals about all areas of government, I'd know what was going on,” Ms Carter said of her years of service.
Two years into the Carter presidency, Time magazine called her the “second most powerful person in the United States”.
She also brought national attention to the performing arts, which is documented in the film Jimmy Carter: Rock 'n' Roll President.
Ms Carter and her husband hosted many barbecues and concerts during their time in Washington, with guests including Paul Simon, Aretha Franklin, the Atlanta Rhythm Section, Dizzy Gillespie, Sarah Vaughan, Herbie Hancock, Pearl Bailey and Charles Mingus.
Dolly Parton, Willy Nelson, Bob Dylan and the Allman Brothers were also among the performers to visit the Carters at the White House.
Aid programmes for the elderly and communities in need were also high on Ms Carter’s agenda, although it would be her tireless advocacy for mental health that would be her lasting legacy.
From 1977 to 1978, she served as the honorary chairwoman of the President’s Commission on Mental Health, which resulted in passage of the Mental Health Systems Act of 1980.
After the White House, the Carter Centre and Library was opened in Atlanta, where Ms Carter would work until her death.
The first major project of the centre was aiding peace between Israel and its neighbours.
It was there that Ms Carter created and led the Carter Centre's Mental Health Task Force, advocating positive change in mental health.
She also oversaw the establishment of the Rosalynn Carter Fellowship for Mental Health Journalism, which provides funding to reporters in the US, Europe, the Middle East and elsewhere, covering topics related to mental health or mental illness. Around 250 reporters have been awarded fellowships since the programme's inception in the 1990s, including several journalists in the UAE.
In 2007, Ms Carter and David Wellstone testified before Congress in an effort to pass the Paul Wellstone and Pete Domenici Mental Health Parity and Addiction Equity Act of 2008, which requires equal coverage of mental and physical illnesses when insurance policies include both types of coverage.
And, like her husband, Ms Carter is considered a key figure in the Habitat for Humanity charity.
She and the former president met in their hometown of Plains in 1946.
The couple had four children: John William, known as “Jack” (1947), James Earl III, known as “Chip” (1950), Donnel Jeffrey, known as “Jeff” (1952), and Amy Lynn (1967).
In 1999, Ms Carter was given the Presidential Medal of Freedom, the nation's highest civilian honour, along with her husband.
She received countless accolades for her advocacy, including the Jefferson Award for Greatest Public Service Benefitting the Disadvantaged, the Georgia Woman of the Year Award, the UN children's fund International Child Survival Award, the US Surgeon General's Medallion and the American Peace Award.
She also published five books including an autobiography titled First Lady from Plains and Everything To Gain: Making the Most of the Rest of Your Life.
She is survived by her children, Jack, Chip, Jeff, and Amy, and 11 grandchildren and 14 great-grandchildren.