He was the eldest son of Maximilien Louis van der Noot, 7th Marquess of Assche[2] and his second wife Adelaïde Countess d'Yve de Bavay (1792–1879).
[3] His sister Charlotte, countess van der Noot was married to Count de Lannoy, Lord Marshall to the Duke of Brabant.
Theodore married in Brussels on 14 June 1856 to the Russian Catherine Bernardaki (1825–1905), she was the widow of Gotthard Alexander Konstantin von Benckendorff.
[5] After second world war the Hôtel van der Noot d'Assche [nl] was sold to the Belgian state.
Another residence was the estate of the Chateau des Amerois, sold to Prince Philippe, Count of Flanders, who had the castle built by Gustave Saintenoy.