Goodwill ambassador is a post-nominal honorific title, a professional occupation and/or authoritative designation that is assigned to a person who advocates for a specific cause or global issue on the basis of their notability such as a public figure, advocate or an authoritative expert. Sometimes the role of a goodwill ambassador is presented as "Ambassador" or "Goodwill Ambassador" preceding the first and last name, the titled name of the individual is always presented with an organizational, regional or national affiliation. Goodwill ambassadors generally deliver goodwill by promoting ideals or positions from one entity to another, or to a population to establish a benevolent relationship. A goodwill ambassador may be an individual from one country who resides in or travels to another country on a diplomatic mission (or international friendship mission) at a peer to peer level. This can be country to country, state to state, city to city, or as an intermediate emissary representative of the people of a specific organization or cultural group, such as an indigenous tribe, marginalized people or enclave population.

Goodwill ambassadors have been a part of governments, institutions and countries for as long as diplomacy has existed. They represent their constituents by traveling abroad exchanging or delivering gifts and presents while bringing awareness to their cause or purpose through public relations activities and organizing events. Goodwill ambassadors are responsible for delivering humanitarian relief, implementing social welfare programs and providing development assistance to demonstrate benevolence and compassion between parties. Most often nation-states, international and non-governmental organizations use well-known celebrities such as actors, actresses, musicians, scientists, authors, former politicians and other high society figures; but they also engage civilians, professionals and government officials to fulfill the role.

Goodwill missions of US states and international nations are usually carried out or overseen by the head of state, but do not necessarily involve official diplomatic credentials beyond a letter of presentation, letters patent, or a letter of credence. It is very rare that a goodwill ambassador is ever issued a diplomatic passport. However, some countries, such as Haiti and Saint Lucia do issue credentials that include diplomatic immunity for goodwill ambassadors and organizations sometimes issue a civil service officer credential or international identification travel document such as a laissez-passer.

Recognition as an authority is designated by an official document that entitles the subject to the use of the honorable title or can be developed over time through social media or public relations. The title is closely associated with the personal name, such as (Angelina Jolie, Goodwill Ambassador) or (Angelina Jolie, UNHCR Goodwill Ambassador) or (Goodwill Ambassador Angelina Jolie). Any regional, state, nation or body politic has the authority to officially designate goodwill ambassadors.

Many say the first ambassador of good-will was Ambassador Benjamin Franklin on his mission to France in December 1776, when the United States was just a few months old and embroiled in the Revolutionary War. Others might say it was pioneer Daniel Boone who was hired as a civilian colonel to help Col. Judge Richard Henderson build the Wilderness Road and negotiate with good-will the Treaty of Watauga with the Cherokee to establish the Transylvania Colony on May 23, 1775. At its time, the Transylvania Colony was the first democratic government free of British Monarchy calling for a "manly government", Boonesborough had both indigenous and free slaves as civil participants.

Benjamin Franklin in colonial times was also known as Silence Dogood (a pen name) who wrote a series of letters that were published and widely read. Almost 50 years before the American Revolution Franklin adapted; Bonifacius: Essays to Do Good, by the Puritan preacher and family friend Cotton Mather, which Franklin often cited as a key influence throughout his life. His work preached the importance of forming voluntary associations to benefit society. While Franklin learned about forming do-good associations from Cotton Mather, his benevolence, humility and organizational skills made him the most influential force in making voluntarism an enduring part of the American ethos.

The word "good-will" first appears in American newspapers as early as 1789 in the Gazette of the United-States where the term was associated synonymously with words like benevolence, charity, compassion, delight, divinity, grace, honor, humanity, humility, mankind and virtue all in a single thought.

The term "ambassador of good-will" appears in 1920 discussing a delegation of government supported business people from Texas visiting Mexico and establishing friendly business relationships. The article called for "increasing the ranks of ambassadors of good-will" by inviting other businesses and states to their commission. The term "goodwill ambassador" finally emerges into the international landscape as a highly defining and descriptive term in the early 20th Century through a public figure who later proves to be a controversial one. In December 1927 it was applied to aviator and ambassador, Col. Charles Lindbergh by the international news media when he scheduled an International Goodwill Tour visiting Mexico, Central America, Colombia and Venezuela in the Spirit of St. Louis.