Küster was born in Blomberg, Westphalia. He was friends with, and a correspondent of, Richard Bentley, master of Trinity College, Cambridge, who assisted him in the production of a hasty edition of the works of Aristophanes. Thomas de Quincey was later to say that Bentley's contributions—including epistles on The Clouds and Plutus—were "mangled" by Küster and incompetent printers. Some of these letters still survive. Bentley also assisted Küster, among other editors, with an edition of Suidae Lexicon Graece et Latine (1705).
In Utrecht, from 1697 to 1699, Küster published the journal Bibliotheca Librorum novorum under the pseudonym "Neocorus" (a Greek word that translates as roughly equivalent to the German word "Küster", that is, "sexton" or "sacristan"). Several times, Küster came into professional conflict with Dutch classical scholar Jakob Gronovius.
In 1710, he made a reprint, or rather revision, of John Mill's Novum Testamentum Graecum (1707), with prolegomena and with collations of 12 more manuscripts. It was published in Amsterdam and Rotterdam. Kuster's reprint also appeared, in Leipzig in 1723 and again in Amsterdam in 1746. He used 12 more manuscripts than Mill's original edition. Nine of these 12 codices were collated for Küster by the abbé de Louvois: codex 285, M, 9, 11, 119, 13, 14, 15, and Codex Ephraemi. Currently they are housed in the Bibliothèque nationale de France in Paris. Codex 78 was collated by Boerner, codex 42, and Codex Boernerianus by Küster himself. In this edition, Küster published his own notes separate from Mill's by prefixing and affixing the marks, and his collations both of his own codices and of early editions will be found more complete than his predecessor's. Mill's dedication was omitted.
Küster was the first to recognize the 9th century date of Codex Boernerianus.
In 1713, Küster traveled to Paris and spoke against the Protestant religion. There he was admitted to the Academy of Inscriptions and Belles Lettres, and received a pension from the crown of 2000 pounds.
- A Critical History of Homer, Frankfurt, 1696
- Suidae Lexicon Graece & Latine, ed. Aemilius Portus & Ludolph Kuster, 3 vols, Cambridge 1705.
- An edition of the Life of Pythagoras, Iamblichus and Porphyry, Amsterdam, 1707
- Aristophanes. Commoediae undecim, graece et latine, ex Codd. Mss. emendate: Cum scholiis Antiquis, inter quae scholia Lysistratem ex Cod. Vossiano nunc primum in lucem proderunt, ed. Ludolphus Kusterus, Amsterdam, Thomas Fritsch, 1710.
- Novum Testamentum Graecum, cum lectionibus variantibus mss (Amsterdam & Rotterdam, 1710).
- An edition of Hesychius
- Lud. Kusterus de Vero Usu Verborum Mediorum.
- Pope, Alexander (1888). Selected Poems, The Essay on Criticism, The Moral Essays, The Dunciad. London: Longman. pp. 111, 207–208.
- Wordsworth, C. (1842). The Correspondence of Richard Bentley. London: John Murray. pp. 233–236.
- de Quincey, Thomas (1877). The Eighteenth Century in Scholarship and Literature. Cambridge: Riverside Press. pp. 69–74.
- Bruce M. Metzger, Bart D. Ehrman, The Text of the New Testament: Its Transmission, Corruption and Restoration, Oxford University Press, 2005, p. 154.
- Scrivener, Frederick Henry Ambrose; Edward Miller (1894). A Plain Introduction to the Criticism of the New Testament, Vol. 2. London: George Bell & Sons. p. 204.
- Alexander Reichardt (1909). Der Codex Boernerianus. Der Briefe des Apostels Paulus. Leipzig: Verlag von Karl W. Hiersemann. p. 9.