Kazakh Deputy Foreign Minister Roman Vasilenko said: "The now-former president wants to ensure the smoothest transition of power. . . . The main principles of his domestic and foreign policy will remain intact."
Analysts expect Nazarbayev, who also will continue to hold the title of "Leader of the Nation," to remain the most powerful person in Kazakhstan even after he steps down.
His effort to do so will be watched closely in the region, not least by Russian President Vladimir Putin, who is constitutionally required to leave his post in 2024.
"What happened here is essentially a change in the signage," said Talgat Mamyrayimov, a political scientist based in the Kazakh city of Almaty. Nazarbayev "will continue to rule the country."
But Nazarbayev's resignation comes at a time of flux in Central Asia, adding more political uncertainty to the demographic and geopolitical change sweeping the region's former Soviet republics.
Russian officials have voiced concerns about what they describe as growing nationalism and Western influence in Kazakhstan, stoking speculation about the possibility of pro-Kremlin separatist movements in Kazakhstan's more ethnically Russian north.
China has been expanding its political and economic influence across Central Asia, seeing Kazakhstan as pivotal to its massive One Belt, One Road global infrastructure programme.
Underscoring that geopolitical balancing act, Nazarbayev noted in his speech that Tokayev had studied in Moscow and spoke good English and Chinese.
Nazarbayev talked to Putin by phone, the Kremlin said, illustrating their close personal relationship. But Nazarbayev also has sought to balance Russia's longtime dominance by drawing in Chinese investment and building ties with the West.
In 2017, he ordered the official script of the Kazakh language to be switched from Cyrillic to Latin, an expensive undertaking that infuriated some Russian officials.
Nazarbayev has sought to modernise his oil-and-gas-rich nation's economy, even building Astana virtually from scratch in the northern Kazakh steppe. But his domestic leadership has been decidedly authoritarian, with political dissent and media freedoms severely limited.
"On the ruins of the USSR, we managed to build a successful Kazakh state with a modern market economy, and to create peace and stability inside multiethnic and multireligious Kazakhstan," Nazarbayev said in his speech.
Analysts expect Nazarbayev to pick a successor who would then win a tightly controlled election. Mamyrayimov, the political scientist, said he viewed Nazarbayev's eldest daughter, Dariga Nazarbayeva, as a favourite to take over as president.
But with Kazakhstan's demographics rapidly changing, more nationalist, religious or pro-Western groups could pose a challenge to Nazarbayev's succession plan.
The number of ethnic Kazakhs, whose language is related to Turkish and who are largely Muslim, has rapidly grown. The share of ethnic Russians, whose numbers roughly equalled those of the Kazakhs when the Soviet Union fell in 1991, has sharply fallen.
"Total state control in our country will most likely strengthen in order to clear the political field of potential competitors," Mamyrayimov said.
