Rosalynn Carter developed her public work through business, political campaigning, and advocacy for overlooked groups. After the Carters returned to Plains, Georgia, in 1953, she managed accounts for the family peanut enterprise. She became an important campaigner in Jimmy Carter's races for governor and president, speaking to voters and reporting concerns she encountered on the road.

As Georgia's first lady from 1971 to 1975, she worked on mental health services and served on the governor's commission dealing with the subject. She also sought better conditions and opportunities for women in prison. Her advocacy emphasized community services and the difficulties faced by people living with mental illness and their families.

In the White House from 1977 to 1981, Carter was a close presidential adviser and an unusually visible participant in policy discussions. She represented the administration on a 1977 journey to seven Latin American countries, discussing human rights and other diplomatic concerns with national leaders. As active honorary chair of the President's Commission on Mental Health, she promoted its recommendations and supported the Mental Health Systems Act of 1980. She also advocated the Equal Rights Amendment and assistance for Cambodian refugees.

After leaving Washington, she and her husband founded the Carter Center in 1982. There she chaired a mental health task force and convened specialists, advocates, and people with lived experience to improve treatment and reduce stigma. The Rosalynn Carter Institute for Caregivers, established in 1987, addressed the pressures on family caregivers. She and Betty Bumpers launched Every Child By Two in 1991 to encourage timely childhood vaccination. With Jimmy Carter she also volunteered on Habitat for Humanity building projects. Her books, including First Lady from Plains and practical works on caregiving and mental illness, extended these concerns to readers beyond the policy community.