Mattheson befriended George Frideric Handel (Handel, George Frideric) while serving as a singer and conductor at the Hamburg Opera. In 1706 he became secretary to the English ambassador, and he later served as ambassador ad interim. He was cantor and organist at Hamburg cathedral from 1715 to 1728, when his deafness forced him to resign.

Mattheson's compositions include oratorios, operas, and instrumental works, but his influence lies mainly in his scholarly writings. Most notable is a biographical dictionary, Grundlage einer Ehrenpforte (1740; “Foundation of a Triumphal Arch”), which includes 148 composers. Also among his writings are two works on the basso continuo and Der vollkommene Kapellmeister (1739; “The Complete Chapel-Master”), an encyclopaedia of his musical ideas. Mattheson advocated the merging of the separate Italian, French, and German styles into an integrated musical style and felt that sacred music could be revitalized by the inclusion of secular elements (e.g., operatic elements in church cantatas). His translations from English to German include John Mainwaring's biography of Handel and Daniel Defoe's Moll Flanders.