There is relatively little we can say about Mysliveček's life with absolute certainty, and he remains largely shrouded in mystery.  In comparison with other composers, period documents and letters are scarce, and we know practically nothing about his personal life in adulthood. His music, however, which continues to speak to us with immense force and eloquence, has been preserved almost in its entirety.

Josef Mysliveček was most likely born in Sova Mills in Kampa on 9 March 1737. His father was Matěj Mysliveček, a wealthy and influential miller. Mysliveček's mother, Anna Terezie, also came from a family of millers. In addition to a twin brother, Jáchym, Mysliveček also had a sister, Maria Anna, who entered a convent in adulthood. Jáchym made his living as a miller in Prague until his death. We know for a fact that the family was wealthy and materially sound, with Mysliveček's father buying, among other property, the “U Modrého šífu” house (Blue Ship House) in the Old Town (now Melantrichova 13). Josef likely attended a Dominican school at the Church of St. Giles, where he also probably went to music lessons. Afterwards, he would appear to have switched to the Jesuit college in Klementinum, where great emphasis was placed on the musical preparation of its students. We know that he enrolled at Charles-Ferdinand University but left after the first year because he “made no progress in logic”. He subsequently learned the trade of miller, studying hydraulics and mathematical subjects, among others, as required of the millers of that time. He successfully completed his studies, was admitted to the Prague Guild as a master miller and began working in the family mills. 

Mysliveček did not focus on music until he was twenty-five, at which stage he suddenly decided to change his path in life and become a composer and violin virtuoso. It is possible that he was influenced in his decision by the fact that Italian operas were once again being performed in Prague at that time after a forced absence caused by the Seven Years’ War. These productions likely caught his attention so much that he decided to make his mark on the genre himself.

He first completed his musical education in Prague with František Václav Habermann and Josef Seger and began writing his own compositions surprisingly quickly – his oldest surviving work is the successful Symphony in C major. However, an Italian education was indispensable for opera composers of that time and Mysliveček, like other important musicians from the Czech lands, such as Christoph Willibald Gluck, who spent his childhood and youth in Chřibská near Děčín and at the manor in Jezeří, and native of the town of Most Leopold Gassmann, departed for Italy.

Mysliveček left for Italy in the autumn of 1763 with the support of prominent patron of the arts Count Vincent of Wallenstein. He went to Venice, probably because the Italian operas which were performed in Prague, and the vocalists who sang in them, were often of Venetian provenance. In 1766, about two and a half years after his arrival in Venice, his first opera Semiramide was staged in Bergamo, and met with considerable success, bringing Mysliveček further opportunities, including an invitation to compose an opera for Naples.

During his time in Italy, Mysliveček travelled from city to city, composed for various theatres, and never accepted a permanent position. He was primarily associated with the Neapolitan Teatro San Carlo, which was the most prestigious European stage of its time in terms of Italian opera seria. It was in this esteemed theatre that more of Mysliveček’s operas were performed than anywhere else. 

Mysliveček's first opera for Naples, Il Bellerofonte, met with an enthusiastic reception. The main roles were sung by tenor Anton Raaff and soprano Caterina Gabrielli, two of the most famous opera stars of the age, and Mysliveček went on to work with them many times in the future. Other favourite collaborators included Luigi Marchesi, one of the most admired male sopranos (castrati) of that time. The positive response to the opera led to commissions for many other Italian theatres, including Florence, Rome, Venice, Turin, and Bologna. 

Mysliveček also achieved great success in Munich, where his opera Ezio was performed in 1777, as was his oratorio Isacco, figura del redentore, which Wolfgang Mozart suggested in a letter that "the whole of Munich" was still talking about even six months later.

Mysliveček first met Wolfgang Mozart and his father Leopold in Bologna in 1770. He is mentioned in twenty-eight of the surviving letters from the Mozart family correspondence from between 1770 and 1778, although even this significant amount of correspondence is probably only a fraction. We can only guess at the actual level of personal contact and the number of letters involved. In 1770, Wolfgang Mozart, aged 14, worked on the opera Mitridate, re di Ponto, which was to be performed in Milan.
Mysliveček was an important mentor to Mozart at that time, introducing him to the latest trends in composing Italian opera seria. Mozart's Mitridate can be described without exaggeration as a “Mysliveček” work, with Mozart borrowing a number of musical ideas from Mysliveček's opera La Nitteti for his own opera.
Mysliveček and Wolfgang Mozart met for the last time in Munich, at which time Mysliveček was already seriously ill. Mozart visited him in hospital and wrote about the meeting in a letter to his father in much detail and with great emotion.
The friendship between Mysliveček and the Mozarts was later to cool when Mysliveček was unable to make good on his promise of getting Wolfgang a commission for an opera at Teatro San Carlo. Mozart returned to the genre of opera seria at the end of his life, when he composed the opera La clemenza di Tito, which premiered at the Estates Theatre in Prague in 1791 on the occasion of the coronation of Leopold II as Bohemian king. Mysliveček composed music for the same libretto some seventeen years earlier.

In the final years of his life, Mysliveček suffered from major health problems and pain caused by a progressive disease, most likely syphilis. Despite this, however, he continued to compose operas and instrumental pieces. Three years before his death, he presented one of his best operas of all, L'Olimpiade, which was played in honour of the nameday of the King of Spain. One comment from the time states: The famous aria "Se cerca, se dice", in particular the second part "Che abisso di pene, lasciare il suo bene", was received with awe, bordering on frenzy. 
The music Mysliveček wrote for this aria is truly a masterpiece of the most beautiful and eloquent vocal style and uses a completely new and very complex accompaniment.

In addition to illness, Mysliveček also had financial problems and had to resort to taking out several loans from a bank for the poor.
It is not known exactly when he died, but there is a record of a funeral which took place in Rome in the Church of San Lorenzo in Lucina on 4 February 1781. This date was soon accepted as the date of his death. He left behind virtually no possessions, and the priest who recorded his funeral took Mysliveček to be a 65-year-old man, when in reality the composer did not even live to the age of forty-four.

Compiled from Daniel E. Freeman’s guidebook Il Boemo: průvodce po životě a díle Josefa Myslivečka (Vyšehrad, 2021) and the monograph Josef Mysliveček, "Il Boemo" (Calumet Editions, 2023).