In the course of the fierce Investiture Controversy, the rise of the comital dynasty continued with the appointment of Siegbert's son Adalbert as Archbishop of Mainz in 1111, and in 1118 his elder brother Frederick was first mentioned with the title of a "Count of Saarbrücken". However, Frederick's son Simon I had to face the slighting of his Saarbrücken residence by the forces of Emperor Frederick Barbarossa in 1168. Upon his death about 1183, the county was divided into two parts, when the Palatinate territories were separated to form the basis of the County of Zweibrücken. The Alsatian possessions had been lost already around 1120.
When the comital House of Leiningen became extinct in 1212, the Counts of Saarbrücken by jure uxoris inherited their Palatinate possessions around Altleiningen Castle, where they established the younger line of the Counts of Leiningen as a cadet branch. Simon III of Saarbrücken, count from 1207, was a loyal supporter of the Imperial House of Hohenstaufen and of Philip of Swabia. He later joined the Fifth Crusade and, as he had no male heirs, reached the acknowledgement of the inheritance by his daughter Laurette. His younger daughter Mathilda, who succeeded her sister in 1272, managed to secure her right of succession by marrying Count Simon of Commercy who from 1271 called himself Count of Saarbrücken-Commercy.
Philipp I ruled both Nassau-Saarbrücken and Nassau-Weilburg and in 1393 inherited through his wife Johanna of Hohenlohe the lordships of Kirchheimbolanden and Stauf. He also received half of Nassau-Ottweiler (Lordship of Ottweiler [de]) in 1393 and other territories later during his reign. After his death in 1429 the territories around Saarbrücken and along the Lahn were kept united until 1442, when they were again divided among his sons into the lines Nassau-Saarbrücken (west of the Rhine) and Nassau-Weilburg (east of the Rhine), the so-called Younger line of Nassau-Weilburg.
In 1507 Count John Ludwig I significantly enlarged his territory by marrying Catharine, the daughter of the last Count of Moers-Saarwerden and in 1527 inherited the County of Saarwerden including the Lordship of Lahr. Though after his death in 1544 the county was split into three parts, the three lines (Ottweiler, Saarbrücken proper and Kirchheim) were all extinct in 1574 and all of Nassau-Saarbrücken was united with Nassau-Weilburg until 1629. This new division however was not executed until the Thirty Years' War was over and in 1651 three counties were established: Nassau-Idstein, Nassau-Weilburg and Nassau-Saarbrücken.
By 1728 Nassau-Saarbrücken was united with Nassau-Usingen which had inherited Nassau-Ottweiler and Nassau-Idstein. In 1735 Nassau-Usingen was divided again into Nassau-Usingen and Nassau-Saarbrücken. In 1793 the territories of Nassau-Saarbrücken were occupied (along with the rest of the Left Bank of the Rhine) by the French First Republic; in 1797 Saarbrücken was annexed to the Sarre department.
