The Tsardom of Russia, also known as the Tsardom of Moscow, was the centralized Russian state from the assumption of the title of tsar by Ivan IV in 1547 until the foundation of the Russian Empire by Peter the Great in 1721.

From 1550 to 1700, Russia grew by an average of 35,000 square kilometres (14,000 sq mi) per year. The period includes the upheavals of the transition from the Rurik to the Romanov dynasties, wars with the Polish–Lithuanian Commonwealth, Sweden, and the Ottoman Empire, and the Russian conquest of Siberia, to the reign of Peter the Great, who took power in 1689 and transformed the tsardom into an empire. During the Great Northern War, he implemented substantial reforms and proclaimed the Russian Empire after victory over Sweden in 1721.

While the oldest endonyms of the Grand Principality of Moscow used in its documents were "Rus'" (Русь) and the "Russian land" (Русская земля, Russkaya zemlya), a new form of its name in Russian became common by the 15th century. The vernacular Rus' was transformed into Rus(s)iya or Ros(s)iya (based on the Greek name for Rus'). In the 1480s, Russian state scribes Ivan Cherny and Mikhail Medovartsev mention Russia under the name "Росиа" (Rosia), and Medovartsev also mentions the sceptre "of Russian lordship" (Росийскаго господства, Rosiyskago gospodstva). In the following century, the new forms co-existed with Rus' and appeared in an inscription on the western portal of the Transfiguration Cathedral of the Spaso-Preobrazhensky Monastery in Yaroslavl (1515), on the icon case of the Theotokos of Vladimir (1514), in the work by Maximus the Greek, the Russian Chronograph written by Dosifei Toporkov (died 1543 or 1544) in 1516–1522, and in other sources.

On 16 January 1547, Ivan IV was crowned the tsar and grand prince of all Russia (Царь и Великий князь всея Руси, Tsar i Velikiy knyaz vseya Rusi), thereby proclaiming the Tsardom of Russia, or "the Great Russian Tsardom", as it was called in the coronation document, by Constantinople Patriarch Jeremiah II, and in numerous official texts. The formula in manuscripts "to all his state of Great Russia" later replaced those found in other manuscripts – "to all the Russian realm" (vo vse Rossisskoe tsarstvo); the former is more typical of the 17th century, when the usage of the term "Great Russia" (Velikaya Rossiya) became widely established. By the 17th century, the form Rossiya replaced Rus' to describe the extent of the tsar's imperial authority in chiny, with Feodor III using the term "Great Russian Tsardom" (Velikorossisskoe tsarstvie) to denote an imperial and absolutist state, subordinating both Russian and non-Russian territories. The old name Rus' was replaced in official documents, though the names Rus' and Russian land were still common and synonymous to it.

The Russian state partly remained referred to as Moscovia (English: Muscovy) throughout Europe, predominantly in its Catholic part, though this Latin term was never used in Russia. The two names Russia and Moscovia appear to have co-existed as interchangeable during the late 16th century and throughout the 17th century with different Western maps and sources using different names, so that the country was called "Russia, or Moscovia" (Latin: Russia seu Moscovia) or "Russia, popularly known as Moscovia" (Latin: Russia vulgo Moscovia). In England in the 16th century, it was known both as Russia and Muscovy. Such notable Englishmen as Giles Fletcher, author of the book Of the Russe Common Wealth (1591), and Samuel Collins, author of The Present State of Russia (1668), both of whom visited Russia, were familiar with the term Russia and used it in their works. So did numerous other authors, including John Milton, who wrote A brief history of Moscovia and of other less-known countries lying eastward of Russia, published posthumously, starting it with the words: "The Empire of Moscovia, or as others call it, Russia...".

According to prominent historians like Alexander Zimin and Anna Khoroshkevich, the continuous use of the term Moscovia was a result of traditional habit and the need to distinguish between the Muscovite and the Lithuanian part of Rus', as well as of the political interests of the Polish–Lithuanian Commonwealth, which competed with Moscow for the western regions of Rus'. Due to the propaganda of the Commonwealth, as well as of the Jesuits, the term Moscovia was used instead of Russia in many parts of Europe where prior to the reign of Peter the Great there was a lack of direct knowledge of the country. In Northern Europe and at the court of the Holy Roman Empire, however, the country was known under its own name, Russia or Rossia. Sigismund von Herberstein, ambassador of the Holy Roman Emperor in Russia, used both Russia and Moscovia in his work on the Russian tsardom and noted: "The majority believes that Russia is a changed name of Roxolania. Muscovites ("Russians" in the German version) refute this, saying that their country was originally called Russia (Rosseia)". Pointing to the difference between Latin and Russian names, French captain Jacques Margeret, who served in Russia and left a detailed description of L'Empire de Russie of the early 17th century that was presented to King Henry IV, stated that foreigners make "a mistake when they call them Muscovites and not Russians. When they are asked what nation they are, they respond 'Russac', which means 'Russians', and when they are asked what place they are from, the answer is Moscow, Vologda, Ryasan and other cities". The closest analogue of the Latin term Moscovia in Russia was "Tsardom of Moscow", or "Moscow Tsardom" (Московское царство, Moskovskoye tsarstvo), which was used along with the name "Russia", sometimes in one sentence, as in the name of the 17th century Russian work On the Great and Glorious Russian Moscow State (О великом и славном Российском Московском государстве, O velikom i slavnom Rossiyskom Moskovskom gosudarstve).

By the 16th century, the Russian ruler had emerged as a powerful, autocratic figure, a Tsar. By assuming that title, the sovereign of Moscow suggested that he was a major ruler or emperor on a par with the Byzantine emperor. Tsar (царь) represents the Slavic adaptation of the Roman Imperial title/name Caesar) Indeed, after Ivan III married Sophia Palaiologina, the niece of the late Byzantine Emperor Constantine XI Palaiologos, in 1472, the Moscow court adopted Byzantine terms, rituals, titles, and emblems such as the double-headed eagle, which survives in the coat of arms of Russia. The Byzantine Empire was ready to be succeeded since it had been conquered by the Ottoman Empire in 1453.

At first, the Byzantine term autokrator expressed only the literal meaning of an independent ruler, but in the reign of Ivan IV (1533–1584) it came to imply unlimited (autocratic) rule. In 1547 the Grand Duke Ivan IV was crowned Tsar and thus was recognized – at least by the Russian Orthodox Church – as Emperor. Notably, the hegumen Philotheus of Pskov claimed in 1510 that after Constantinople fell to the Ottoman Empire, the Russian tsar remained the only legitimate Orthodox ruler, and that Moscow was the Third Rome, becoming the final lineal successor to Rome and Constantinople; these were the two centers of Christianity and of the Western and Eastern Roman empires of earlier periods. The "Third Rome" concept would resonate in the self-image of the Russian people in future centuries.