President Vladimir Putin on Wednesday appointed deputy finance minister
"You haven't been working long, but... you are working successfully," Putin told Oreshkin at a meeting, quoted on the Kremlin website.
"I want to offer you the position of economic development minister."
The new economy minister is just 34 years old and worked in the banking sector before joining the finance ministry in 2013. He was appointed deputy finance minister last year.
The finance and economic development ministries are two separate entities in Russia.
Putin commented on Oreshkin's age saying that "you are a quite young person," but praised him as "a mature, experienced specialist."
Oreshkin has been tasked with pulling the country out of a two-year recession exacerbated by depressed prices for its key oil exports and Western sanctions over Ukraine.
He told Putin on Wednesday: "The worst is now over but the growth rates are still, of course, insufficient."
"Therefore the main task for the next year is to prepare key measures that will remove structural obstacles to the Russian economy's growth and let it move forward."
His predecessor Ulyukayev, 60, is currently under house arrest after being slapped with bribe-taking charges that shocked the liberal wing of the government, with Prime Minister Dmitry Medvedev saying his fall from grace was "beyond comprehension."
The FSB security service dramatically detained Ulyukayev in the early hours of November 15 for allegedly accepting a bribe to greenlight state oil giant Rosneft's acquisition of the state-owned majority stake in Russian oil company Bashneft for $5.2 billion.
He had served as economy minister since 2013.