As a career bureaucrat who has been in charge of Russia's taxes for the past 10 years, Mishustin has always kept a low profile.
Mikhail Mishustin never had any political ambitions as a career bureaucrat and his name didn't come up as a top candidate to become Russia's next prime minister.
But the 53-year-old Mishustin, the longtime chief of Russia's tax service, was tapped for the post by President Vladimir Putin. The lower house of Russia's parliament, the Duma, quickly appointed Mishustin as prime minister on Thursday.
Putin put Mishustin's candidacy forward on Wednesday night, several hours after Dmitry Medvedev resigned along with the whole Cabinet. Just before that, Putin proposed sweeping changes to the constitution that could keep him in power well past the end of his term in 2024.
As a career bureaucrat who has been in charge of Russia's taxes for the past 10 years, Mishustin has always kept a low profile and stayed away from politics. He doesn't belong to a political party and in rare interviews prefers to talk about innovations in tax administration.
The move sent shockwaves through Russia's political elite and left them pondering about future Cabinet appointments.
Mishustin has been hailed for modernizing Russia's rigid tax administration system and boosting tax collection rates. Government officials and businessmen describe him as a professional and effective manager who understands the economy well, which makes him a good fit for the Cabinet during a time when Russia's economy is weakened.
"The main tasks for the new prime minister will come from the necessity to modernize the economy," Abbas Gallyamov, a former Kremlin speech writer turned independent political analyst, wrote in a Facebook post. "Mishustin has a reputation of a person who has this experience."
Mishustin's lack of political ambition or any political experience indicates that he is likely to dutifully carry out the Kremlin's wishes as the head of the Cabinet — which some commentators point out is especially important in the "transition period" of constitutional reforms proposed by Putin.
Mishustin, who has a degree in information technology, has been a state official for the past two decades. His career kicked off in 1998, when he became deputy head of the State Tax Service.
Although not active in politics, he has rubbed shoulders or even collided with politicians as a player in the amateur Night Hockey League, in which Putin also plays. Mishustin also is a board member of Moscow's CSKA hockey team.
In 2010, after a two-year stint at a private investment firm, Mishustin returned to the tax service, this time as its chief and handpicked by Putin, then himself a prime minister. Having earned around $2.6 million in 2009, Mishustin was the third-richest state official in Russia at the time.
Over the years, Mishustin "has created a cutting-edge tax service from the ground up, using modern technologies and (means of) digital economy," said Vyacheslav Volodin, the speaker of Russia's lower house of parliament.
Under Mishustin, the tax service launched two vast data centers that collected invoices from businesses and information from retail cash registers, ensuring better control of cash flows. Mishustin also introduced a variety of online services that made paying taxes easier in an effort to raise tax collection rates.
In November, he proudly reported that the amount of successfully collected taxes had increased by 1.4 times since 2014. The share of tax revenues in the country's gross domestic product had also grown by 4 percentage points, while value-added tax collection rose by 64 percent.
Mishustin's track record inspired hopes that as prime minister, he would be able to shake up the country's stagnating economy — something Russians have been increasingly frustrated about in recent years.