Simon III was the eldest son of Simon II (de) (d.1207), Count of Saarbrücken (in office 1183–1207) and Count jure uxoris of Leiningen, and his wife Liutgard of Leiningen (d.a.

When Liutgard's relative Friedrich (First cousin of Emich III) died c. 1215, she inherited the County of Leiningen.

In the struggle about the power in the Holy Roman Empire 1208–1215, he sided with the Hohenstaufen.

Frederick II, Duke of Lorraine[4] with whom he had five children: After the death of his son Dietrich in 1227, he chose Laurette as his heiress as Countess of Saarbrücken, with an official statement in 1235 with the Bishop of Metz, and gave a part of the county to each of the daughters (mentioning "Joffroi d´Aspremont, Lorate, Mahaus & Jehane").

Mathilde gained the title as Countess of Saarbrücken, but the inheritance was contended by Bishop Lorenz von Leistenberg, and first Mathilde's son Simon IV could safeguard their reign after her death, and the House of Saarbrücken-Commercy prevailed until 1381, when the male line became extinct.