Ritter was born in Quedlinburg, one of the six children of a well-respected doctor, F.W. Ritter. Ritter's father died when he was two. At the age of five, he was enrolled in the Schnepfenthal Salzmann School, a school focused on the study of nature (apparently influenced by Jean-Jacques Rousseau's writings on children's education). This experience would influence Ritter throughout his life, as he retained an interest in new educational modes, including those of Johann Heinrich Pestalozzi. Indeed, much of Ritter's writing was based on Pestalozzi's three stages in teaching: the acquisition of the material, the general comparison of material, and the establishment of a general system.

After completion of his schooling, Ritter was introduced to Bethmann Hollweg, a banker in Frankfurt. It was arranged that Ritter should become tutor to Hollweg's children, but that in the meantime he should attend the University of Halle at his patron's expense. His duties as tutor began in 1798 and continued for fifteen years. The years 1814-1819, which he spent at Göttingen in order still to watch over his pupils, were those in which he began to exclusively study geography. It was there where he courted and married Lilli Kramer, from Duderstadt, and where he wrote and published the first two volumes of his Erdkunde.

In 1819 he became professor of history at Frankfurt, and in 1820 he received a teaching appointment in history at the University of Berlin. Ritter received his doctorate there in 1821, and was appointed professor extraordinarius in 1825. He also lectured at a nearby military college. He was particularly interested in the exploration of Africa and held constant contacts with British scholars and scientific circles like the Royal Geographical Society. He was one of the academic teachers of the explorer Heinrich Barth, who traveled in Northern and Western Africa on behalf of the British government to negotiate treaties that were to stop the Trans-Saharan slave trade. Carl Ritter himself was a dedicated anti-slavery and anti-racism propagandist in Germany.

In 1822 Ritter was elected to the Prussian Academy of Sciences, and in 1824 he became a corresponding member of the Société Asiatique de Paris. In 1828, he established the Gesellschaft für Erdkunde zu Berlin (Berlin Geographical Society). In 1856, he was appointed curator of the Royal Cartographic Institute of Prussia.

In 1865, a monument to Ritter was installed at the entrance to the Bruehl in Quedlinburg. The house where he was born, number 15 Steinbrücke, was torn down in 1955. There is an additional monument at the Mummental school honoring both Ritter and his teacher Johann Christoph Friedrich GutsMuths. The Ritter Range in California is named after him.

Ritter's masterwork, the 19-volume Die Erdkunde im Verhältniss zur Natur und zur Geschichte des Menschen (The Science of the Earth in Relation to Nature and the History of Mankind), written 1817-1859, developed at prodigious length the theme of the influence of the physical environment on human activity. Despite its length, the work was left incomplete at the time of his death, covering only Asia and Africa.

Ritter's impact on geography was especially notable because he brought forth a new conception of the subject. In his view, "geography was a kind of physiology and comparative anatomy of the earth: rivers, mountains, glaciers, &c., were so many distinct organs, each with its own appropriate functions; and, as his physical frame is the basis of the man, determinative to a large extent of his life, so the structure of each country is a leading element in the historic progress of the nation." "The earth is a cosmic individual with a particular organisation, an ens sui generis with a progressive development: the exploration of this individuality of the earth is the task of geography". Ritter's writings thus also had implications for political theory. His organic conception of the state could be abused to justify the pursuit of lebensraum, even at the cost of another nation's existence, because conquest was seen as a biological necessity for a state’s growth. His ideas were adopted and transformed into an expansionist ideology by the German geostrategist Friedrich Ratzel. It is to be doubted, however, whether Carl Ritter can be held responsible for this interpretation, which was developed under the influence of Darwinism, which was to become a leading and popular ideology in Germany only after Ritter's death.