With his brother John James Chalon (1778–1854), Alfred became an artist. Entered at the Royal Academy in 1797, he joined the Associated Artists in Water-Colours, a group of aquarellists. In the Academy, he was elected an associat (ARA) in 1812, then academician (RA) in 1816.
Known for his portraits of the good society of London, he was chosen by Queen Victoria to paint a gift to her mother: Victoria in her State robes going to the House of Lords for her first official act, the prorogation of the Parliament, on 17 July 1837. After this task, Chalon was entitled Portrait Painter in Water Colour to Her Majesty and gained some celebrity. His 1837 portrait was engraved by Samuel Cousins and distributed to the public the day of Victoria's coronation, the 28 June 1838. Then, starting in 1851, the "Chalon head" appeared on some British colonies postage stamps.