Joachim Ernst was born at Dessau on 21 October 1536, the second son of Johann IV, Fürst (Prince) von Anhalt-Zerbst, and his wife Margareta von Brandenburg.
He succeeded his elder brother Karl, as Prince of Anhalt in Zerbst, Bernburg and Köthen in 1561. His younger brother Bernhard, succeeded in Dessau in 1565, but this also reverted to Joachim Ernst on Bernhard's death in 1570, uniting all of Anhalt in his hands.
However on the death of Joachim Ernst, Anhalt was again divided between his sons.
Joachim Ernst married firstly, 3 March 1560 at Barby, Agnes von Barby, (born 23 June 1540 at Barby, died 27 November 1569 at Bernburg, and was buried in Schlosskirche, Nienburg).
They had 6 children;
Anna Marie, born 13 June 1561 at Zerbst;
Agnes, born 16 September 1562 at Zerbst, died young on 4 June 1564 at Bernburg, buried Schlosskirche, Bernburg;
Elisabeth, born 25 September 1563 Zerbst
Sibylle, born 28 September 1564 Bernburg;
Johann Georg I, born 9 May 1567 Harzgerode, succeeded as Prince of Anhalt in Dessau;
Christian I, born 11 May 1568 in Bernburg, succeeded as Prince of Anhalt in Bernburg.
He married secondly 9 January 1571 at Stuttgart, Eleonore von Württemberg (born 21 March 1552 Tübingen)
They had 10 children;
Bernhard, born 25 September 1571 at Dessau, died 24 November 1596 at Klosterhof, near Tyrnau, and was buried at Schlosskirche, Dessau;
Agnes Hedwig, born 12 February 1573 Dessau;
Dorothea Maria, born 2 July 1574 at Dessau;
August, born 14 July 1575 Dessau, succeeded as Prince of Anhalt in Plötzkau;
Rudolf, born 28 October 1576 , succeeded as Prince of Anhalt in Zerbst;
Johann Ernst, born 1 May 1578 Dessau, died 12/22 December 1601 Vienna, buried Schlosskirche, Dessau;
Ludwig, born 17 June 1579 at Dessau, succeeded as Prince of Anhalt in Köthen;
Sabine, born 7 November 1580 Dessau, died 28 March 1599 at Darmstadt;
Joachim Christoph, born 7 July 1582 Dessau, died young 16 July 1583 at Dessau, buried Schlosskirche there;
Anna Sophie, born 15 June 1584 Dessau.
Schwennicke, Detlev, Europäische Stammtafeln, Neue folge, Band I.2, Frankfurt am Main: Vittorio Klostermann, 1999. Tafel 188-194.