He was born into a Baltic German family in Arensburg, Governorate of Livonia, and studied at the Imperial Academy of Arts. As a natural son of Baron von Osten-Sacken, he received the name Osteneck, which he later chose to render into Russian as Vostokov (Ost, the German word for "east," translates to vostok in Russian). He liked to experiment with language and, in one of his poems, introduced the female name Svetlana, which would gain popularity through Zhukovsky's eponymous ballad.
During his lifetime, Vostokov was known as a poet and translator, but it is his innovative studies of versification and comparative Slavonic grammars which proved most influential. In 1815, he joined the staff of the Imperial Public Library, where he discovered the most ancient dated book written in Slavonic vernacular, the so-called Ostromir Gospel. In 1841, Vostokov was elected to the Russian Academy of Sciences.
Vostokov's works on the Church Slavonic language were considered a high-water mark of Slavic studies until the appearance of Izmail Sreznevsky's comprehensive lexicon in 1893–1903 and garnered him the doctorates honoris causa from the Charles University and University of Tübingen.
Vostokov also laid foundations of modern Russian toponymy. In 1812, he published a paper with the title "An example to the amateurs of etymology" (Russian: Задача любителям этимологии), where he argued that geographical names (toponyms) have repeating elements which he called formants and which help to restore the etymology of the name. For instance, the endings -va, -ga, and -ma in the end of such names as the Kama, the Sylva, and the Onega, may mean "water" in the languages these names originate from. Whereas this paper did not get sufficient attention during Vostokov's life, it did subsequently receive recognition, and Vostokov is cited as one of the founders of toponymy in Russia.
- Востоков Александр Христофорович (1781–1864) (in Russian). Moscow: Учреждение Российской академии наук Институт русского языка им. В. В. Виноградова РАН и ООО "Словари.ру". Retrieved 7 January 2012.
- Востоков, Александр Христофорович (1812). Задача любителям этимологии. Сакт-Петербургский вестник (in Russian). Saint Petersburg. 4.1. (2): 204–288.
- Полищук, В. В. Древние тайны русского слова "Тюмень" (in Russian). ИА Трейд.Су. Retrieved 7 January 2012.
- Успенский, Лев Васильевич (2008). Загадки топонимики. Аванта: Мир Энциклопедий (in Russian). Moscow: ВКТ Владимир. p. 260. ISBN 978-5-17-058250-1.