It was while he was a student at Leipzig University that a career in music became inevitable. At first it was intended that he should study language and science, but he was already so capable a musician that within a year of his arrival he founded the student Collegium Musicum with which he gave public concerts (and which Bach was later to direct), wrote operatic works for the Leipzig Theater, and in 1703 became musical director of the Leipzig Opera and was appointed organist at the Neue Kirche in 1704. While at the University he involved fellow-students in a great deal of public performance, to the annoyance of the Thomaskantor, Bach's immediate predecessor, Kuhnau, who saw his prerogative now infringed.

No doubt bored with the complaints of Kuhnau and impatient to make something more of his life, Telemann did not stay long in Leipzig. In 1705 he accepted an appointment as Kapellmeister to the cosmopolitan court of Count Erdmann II of Promnitz at Sorau (now Zary), where the vogue for the French and Italian styles provided him with a new challenge. His association with the Sorau Kantor and theorist Wolfgang Caspar Printz and the reformist poet Erdmann Neumeister as well as the proximity to Berlin and contact with Polish folk music all proved stimulating. But Telemann's tenure was cut short by the imminent prospect of invasion by the Swedish army, causing the Court to be hurriedly disbanded. He visited Paris in 1707.

His next appointment was at Eisenach as court Konzertmeister in charge of singers, with Pantaleon Hebenstreit as leader of the orchestra. His appointment there (some time between 1706 and 1708) just overlapped with the presence of Bach, who left in 1708 to take up posts at the Weimar court. Telemann had every reason to assume that this would be a period of relative stability and accordingly plunged into composing church cantatas, occasional pieces, orchestral and instrumental chamber music. His marriage ended tragically with his wife's death in 1711.

A change of scene became necessary and so he went to the free imperial city of Frankfurt-am-Main to take up duties as Director of Municipal Music and also as Kapellmeister of the Barfüßerkirche. Together with his activities as director of the "Frauenstein", a musical society in that same city, which presented weekly concerts, Telemann's new posts suited his talents very well. He composed occasional music for civic ceremonies, five year-long cycles of church cantatas, oratorios, orchestral music and a wealth of chamber music, much of which was published; only the opportunity to produce opera was lacking, though he continued to supply works to the Leipzig Opera. During this period he was also appointed Kapellmeister to the Prince of Bayreuth. He married again (gaining citizenship through marriage) and became a family man.

While on a visit to Eisenach in 1716, he was honored with an appointment as a visiting Kapellmeister (he continued to send new works until 1729); he also served the court as a diplomatic correspondent. Further acknowledgment of his increasing stature came the following year when Duke Ernst of Gotha invited him to become Kapellmeister of all his various courts. This in turn forced improvements in his situation at Frankfurt. A trip to Dresden in 1719 for the festivities in honor of the newly married Prince Elector Friedrich August II and Archduchess Maria Josephia of Austria made possible a reunion with Handel, the opportunity to hear operas by Lotti and the dedication of a collection of violin concertos to the Konzertmeister and virtuoso violinist Pisendel.

Then in 1721, the coveted post of Kantor of the Hamburg Johanneum, a post that traditionally carried with it teaching responsibilities and the directorship of Hamburg's five principal churches, became vacant, and Telemann was invited to succeed Joachim Gerstenbüttel. Here, at last, was a prestigious post that would provide him with seemingly unlimited opportunities to compose and perform. As Kantor, he would be stretched as never before: he was required to compose two cantatas a week, annually to produce a new Passion, and to provide occasional works for church and civil ceremonies. And such was his vitality and creative impetus that, in spite of heavy responsibilities, he apparently eagerly sought and fulfilled additional commissions from home and abroad.

The prospect of being actively involved in the Hamburg Opera - his opera Der geduldige Socrates, had already been performed there earlier that year - was perhaps over-optimistic, for there was strong opposition among the city fathers to his participation. Telemann reacted characteristically by threatening to resign: he applied for the post of Kantor of the Leipzig Thomaskirche, and in 1722 was chosen over Bach, Graupner and three other candidates. While the Hamburg City Council refused to grant his release, they were obliged to improve his salary and withdraw their objections to his association with the Hamburg Opera. Telemann thereupon redoubled his activities at Hamburg, increasing the number of public concerts given at the churches, the Drill-Hall and at a tavern known as the 'Lower Tree-House', at which a wide variety of sacred and secular music was performed. They were patronized by prominent Hamburg citizens and supported by paid admission. More to the point, he was made music director of the Hamburg Opera, remaining in that capacity until its closure in 1738. He produced both serious and comic works, many of which have been lost, or survive only as excerpts published in Der getreue Musikmeister. In addition to Telemann's own operas and those of Reinhard Keiser, Handel's London operas were performed there during Telemann's tenure.

Der getreuer Musikmeister ("The Faithful Music Master") was founded in 1728 by Telemann and J.V. Gצrner (not to be confused with J.G. Gצrner, organist at Leipzig and Bach's contemporary). Intended as a "home music lesson", this German music periodical, the first of its kind, appeared every two weeks in the form of a four-page Lection meaning a reading or a lesson. It consisted of actual music, new music just composed and given its first circulation in this unusual fashion. Much of it was by Telemann himself, but other contemporary composers were also represented, such as Keiser, Pezold, Gצrner, Bonporti, Zelenka, Ritter and Stoltzer. Unfortunately the individual issues were not dated, nor is it known how long the periodical appeared for. Twenty-five of these periodicals have come down to us with their contents.

Telemann remained in Hamburg until his death in 1767, being succeeded in that position by his godson, Carl Philipp Emanuel Bach, son of Johann Sebastian. Though it is with Hamburg that we customarily associate his name, Telemann traveled widely, making many trips to Berlin where he was exposed to strains of Polish music imported from the East, and to Paris in 1737 where he absorbed much of the French idiom then current.

Telemann's friendship with Handel continued: Handel corresponded with him on several occasions, and in 1750 went to the trouble of sending him from London "a crate of flowers, which experts assure me are very choice and of admirable rarity". His name appears (as 'Mr. Hendel, Docteur en Musique, Londres') on the list of subscribers to the most ambitious publication of Telemann's music during his lifetime, the Musique de Table, which appeared in three installments during the course of 1733. An interesting side-note is that Telemann supervised the preparation of the engraved plates from which the parts were printed, these being made of pewter as opposed to the more usual and more expensive copper, by a new process apparently first employed in London about 1710 by Walsh and Hare, and introduced into Germany by Telemann himself. Further proof of Handel's esteem for Telemann's music is provided by the fact that Handel used ideas from no less than sixteen movements in the Musique de Table in his own compositions. Handel would jokingly relate that Telemann "could write a church piece in eight parts with the same expedition another would write a letter".

As a composer Telemann was indeed prolific, providing an enormous body of work, both sacred and secular. This included 1043 church cantatas, and settings of the Passion for each year that he was in Hamburg, 46 in all. In Leipzig he had written operas, and he continued to involve himself in public performances in Hamburg, later taking on additional responsibility as musical director of the Hamburg opera. He was also commercially active in publishing and selling much of the music that he wrote.

A musical form which Telemann practiced with remarkable assiduity was the orchestral suite—the Ouverture and its succession of dance movements, which originated with Lully in France but which was in fact cultivated almost exclusively by German composers. A contemporary German critic, Johann Adolph Scheibe, even declared in 1745 that Telemann was chiefly responsible for the enormous popularity of the orchestral suite in Germany, having begun by imitating the French style but soon becoming more expert in it than the French themselves. In an autobiographical article written in 1740 Telemann estimated that he had already composed six hundred suites - about a quarter of which have survived, nearly all in manuscript.

Key factors in Telemann's meteoric rise to power and wealth as the most famous musician in Germany were his sense of humor and likable personality. He had the good fortune to be admired and envied, rather than resented, for his relentless pursuit and acquisition of major Court and Church positions. Telemann's self-confidence and productivity from an early age are extraordinary by any standard. Not only did he have the courage to challenge his superiors when they interfered with his plans to gain frequent performances and publication of his works, but there seemed to be no limit to the number of commissions he was willing and able to fulfill as composer. His salaried income at Hamburg was about three times what Johann Sebastian Bach earned at Leipzig, and he made a substantial profit on his many works published for sale to music enthusiasts.