| Bruno | |
| Succession: | Prince of Ysenburg and Büdingen |
| Reign: | 16 February 1861 – 26 January 1906 |
| Predecessor: | Ernst Casimir II |
| Successor: | Wolfgang |
| Full Name: | Bruno Casimir Albert Emil Ferdinand |
| Spouse: | Princess Mathilde of Solms-Hohensolms-Lich Countess Bertha of Castell-Rüdenhausen |
| Issue: | Princess Hedwig Princess Elisabeth Princess Emma Princess Marie Wolfgang, 4th Prince of Ysenburg and Büdingen Princess Thekla Princess Mathilde Princess Helene Princess Hertha Princess Anna |
| House: | Ysenburg and Büdingen |
| Father: | Ernst Casimir II, 2nd Prince of Ysenburg and Büdingen |
| Mother: | Countess Thekla of Erbach-Fürstenau |
| Birth Date: | 14 June 1837 |
| Birth Place: | Büdingen, (Hesse), Germany |
| Death Place: | Büdingen, (Hesse), Germany |
Bruno Casimir Albert Emil Ferdinand of Ysenburg and Büdingen (14 June 1837 – 26 January 1906) was the third Prince of Ysenburg and Büdingen. Bruno was the eldest son of Ernst Casimir II, 2nd Prince of Ysenburg and Büdingen and his wife Countess Thekla of Erbach-Fürstenau.
As a nobleman, Bruno was a member of the First Chamber of the Estates of the Grand Duchy of Hesse from 1861 to 1906. He served as its president first between 1878 and 1889, and second between 1889 and 1900.
Firstly, Bruno married Princess Mathilde of Solms-Hohensolms-Lich, daughter of Ferdinand, Prince of Solms-Hohensolms-Lich and his wife Countess Caroline of Collalto und San Salvatore, on 31 July 1862 in Lich. Bruno and Mathilde had two daughters before Mathilde's death on 11 September 1867:
∞ Botho, Prince of Stolberg-Rossla (1850–1893) on 27 September 1883 in Büdingen; had issue.
∞ Count Kuno of Stolberg-Rossla (1862–1921) on 31 August 1902 in Rossla; no issue.
∞ Rudolf, Baron of Thüngen (1855–1929) on 25 September 1889 in Büdingen; had issue.
Bruno married secondly to Countess Bertha of Castell-Rüdenhausen, daughter of Adolf, Hereditary Count of Castell-Rüdenhausen and his wife Baroness Marie of Thüngen, on 30 September 1869 in Rüdenhausen. Bruno and Bertha had eight children:
∞ Count Otto of Solms-Laubach (1860–1904) on 14 April 1898 in Büdingen; had issue, among which George Frederick, Count of Solms-Laubach (father of Countess Monika zu Solms-Laubach, wife of Prince Ernest Augustus of Hanover, and maternal grandfather of Countess Donata of Castell-Rüdenhausen).
∞ Countess Adelheid of Rechteren-Limpurg (1881–1970) on 26 September 1901 in Sommerhausen; no issue.
∞ Manfred V, Prince of Collalto and San Salvatore (1870–1940) on 9 May 1901 in Büdingen; had issue.
∞ Cornelius, Baron Heyl of Herrnsheim (1874–1954) on 11 April 1907 in Büdingen; had issue.
∞ Prince Albert of Schleswig-Holstein-Sonderburg-Glücksburg (1863–1948) on 15 September 1920 in Büdingen; had issue.
∞ Count Ernst of Lippe-Weissenfeld (1870–1914) on 21 November 1911 in Büdingen; had issue.
∞ Leopold IV, Prince of Lippe (1871–1949) on 26 April 1922 in Büdingen; had issue.
Bruno studied law at the University of Göttingen. In 1857, he became a member of fraternity Saxonia Göttingen Corps. After graduation, he was Imperial and Royal Major.