Charles D. Bell arrived at the Cape in August 1830, joined the civil service in 1832, and worked in various government offices for two years. In 1834 he received permission to accompany the Expedition for Exploring Central Africa led by Dr. Andrew Smith*. Although he had no formal training in art he was the expedition's second draughtsman. The expedition left Cape Town in July 1834, explored the mountains north of the Orange River, met Chief Moshoeshoe at Thaba Bosiu, travelled to present day Kuruman, explored the Magaliesberg and Pilansberg in the Transvaal, reached the tropic of Capricorn and returned to Cape Town in January 1836. Bell had produced some 300 water colour and pencil illustrations of landscapes, portraits, animals (though most zoological drawings were made by George Ford*), incidents, cultural practices and African artifacts. A number of these were reproduced in Smith's published journal (Lye, 1975), while many of the originals are in the Africana Museum in Johannesburg.
In 1838 Bell qualified as a land surveyor and soon joined the office of the surveyor-general of the Cape Colony, C.C. Michell*. In 1840 he was appointed second assistant surveyor-general of the Cape. During the next few years he undertook surveying expeditions to the Kamiesberg and the eastern frontier, and in 1844 surveyed a new pass at Howiesonspoort. In July 1848 he succeeded Michell as surveyor-general of the Cape Colony and remained in that post until his retirement in December 1872. During August to December 1854 he investigated the copper fields of Little Namaqualand and submitted his report to parliament. It dealt with conflicting land claims in the region, included a sketch map of the district, and gave a good account of the mines and mining methods. The report was published in 1855 together with a report by Commander M.S. Nolloth* on the bays and harbours of the Namaqualand coast.
In 1860 Bell was appointed a member of the Meteorological Committee, founded by the government of the Cape Colony in that year. He remained a member until he retired as surveyor-general. He was also a member of the South African Literary and Scientific Institution (which flourished in Cape Town from 1832 to 1857) and served on its management committee from 1852 to 1855. On 23 June 1855 this committee discussed museum matters in the colony and Bell proposed that, as the government was in the process of forming a museum while the Literary and Scientific Institution did not have the means to preserve its own natural history and other collections, these collections should be transferred to the new government museum. As a result the Institution's collections came to form the nucleus of the South African Museum.
Bell engaged in a variety of other activities. While in Edinburgh in 1847 he learned lithography, brought a press to the Cape and produced lithographs of various South African subjects. He acted as engineer in charge of the Cape Town to Wellington railway (completed in 1863) and as a result the station Bellville was named after him. He became a director of the South African Mutual Life Assurance Society ("Old Mutual") and was its chairman from 1865 to 1873. He was considered an authority on heraldry and provided drawings of the coats of arms of Cape families. In 1850 he painted a number of pictures representing important historical events, including the well-known oil painting depicting the landing of Jan van Riebeeck*. He designed various medals and postage stamps, including the famous Cape triangular postage stamp issued in 1853. After his retirement he returned to Scotland. He was a close friend of C. Piazzi Smyth* from the latter's arrival at the Cape to Bell's death in 1882.