The English physician and Philosopher Sir Thomas Browne penned a discourse entitled The Garden of Cyrus in 1658 in which Cyrus is depicted as an archetypal "wise ruler" – while the Protectorate of Cromwell ruled Britain.

One of the few surviving sources of information that can be dated directly to Cyrus's time is the Cyrus Cylinder (Persian: استوانه کوروش‎), a document in the form of a clay cylinder inscribed in Akkadian cuneiform. It had been placed in the foundations of the Esagila (the temple of Marduk in Babylon) as a foundation deposit following the Persian conquest in 539 BC. It was discovered in 1879 and is kept today in the British Museum in London.

In the 1970s the Shah of Iran adopted the Cyrus cylinder as a political symbol, using it "as a central image in his celebration of 2500 years of Iranian monarchy." and asserting that it was "the first human rights charter in history". This view has been disputed by some as "rather anachronistic" and tendentious, as the modern concept of human rights would have been quite alien to Cyrus's contemporaries and is not mentioned by the cylinder. The cylinder has, nonetheless, become seen as part of Iran's cultural identity.

The United Nations has declared the relic to be an "ancient declaration of human rights" since 1971, approved by then Secretary General Sithu U Thant, after he "was given a replica by the sister of the Shah of Iran". The British Museum describes the cylinder as "an instrument of ancient Mesopotamian propaganda" that "reflects a long tradition in Mesopotamia where, from as early as the third millennium BC, kings began their reigns with declarations of reforms." The cylinder emphasizes Cyrus's continuity with previous Babylonian rulers, asserting his virtue as a traditional Babylonian king while denigrating his predecessor.

The historical nature of this decree has been challenged. Professor Lester L Grabbe argues that there was no decree but that there was a policy that allowed exiles to return to their homelands and rebuild their temples. He also argues that the archaeology suggests that the return was a "trickle", taking place over perhaps decades, resulting in a maximum population of perhaps 30,000. Philip R. Davies called the authenticity of the decree "dubious", citing Grabbe and adding that J. Briend argued against "the authenticity of Ezra 1.1–4 is J. Briend, in a paper given at the Institut Catholique de Paris on 15 December 1993, who denies that it resembles the form of an official document but reflects rather biblical prophetic idiom." Mary Joan Winn Leith believes that the decree in Ezra might be authentic and along with the Cylinder that Cyrus, like earlier rules, was through these decrees trying to gain support from those who might be strategically important, particularly those close to Egypt which he wished to conquer. He also wrote that "appeals to Marduk in the cylinder and to Yahweh in the biblical decree demonstrate the Persian tendency to co-opt local religious and political traditions in the interest of imperial control."

On December 10, 2003, in her acceptance of the Nobel Peace Prize, Shirin Ebadi evoked Cyrus, saying:

The Persian domination and kingdom in the Iranian plateau started by an extension of the Achaemenid dynasty, who expanded their earlier domination possibly from the 9th century BC onward. The eponymous founder of this dynasty was Achaemenes (from Old Persian Haxāmaniš). Achaemenids are "descendants of Achaemenes" as Darius the Great, the ninth king of the dynasty, traces his genealogy to him and declares "for this reason we are called Achaemenids". Achaemenes built the state Parsumash in the southwest of Iran and was succeeded by Teispes, who took the title "King of Anshan" after seizing Anshan city and enlarging his kingdom further to include Pars proper. Ancient documents mention that Teispes had a son called Cyrus I, who also succeeded his father as "king of Anshan". Cyrus I had a full brother whose name is recorded as Ariaramnes.

Cyrus was praised in the Tanakh (Isaiah 45:1–6 and Ezra 1:1–11) for the freeing of slaves, humanitarian equality and costly reparations he made. However, there was Jewish criticism of him after he was lied to by the Cuthites, who wanted to halt the building of the Second Temple. They accused the Jews of conspiring to rebel, so Cyrus in turn stopped the construction, which would not be completed until 515 BC, during the reign of Darius I. According to the Bible it was King Artaxerxes who was convinced to stop the construction of the temple in Jerusalem. (Ezra 4:7–24)

Neil MacGregor, Director of the British Museum, has stated that the cylinder was "the first attempt we know about running a society, a state with different nationalities and faiths — a new kind of statecraft." He explained that "It has even been described as the first declaration of human rights, and while this was never the intention of the document – the modern concept of human rights scarcely existed in the ancient world – it has come to embody the hopes and aspirations of many."