A by-election will be held on October 12 to replace the chairman of the Chukotka Duma, Vasily Nazarenko, who has announced he will step down due to health concerns.
Chukotka governor since 2000, Abramovich, 42, quit his post on July 3. Shortly afterwards, MPs in the regional Duma asked the tycoon to chair the legislature.
Russian President Dmitry Medvedev quickly proposed deputy Chukotka governor Roman Kopin to replace Abramovich, and Chukotka lawmakers approved his candidature in a unanimous vote on July 13.
On Thursday, Kopin's inauguration took place in the capital, Anadyr.
Abramovich, ranked the country's second richest man by Forbes magazine with an estimated $23 billion fortune, has been credited for lavishly investing in sparsely populated Chukotka, a gold- and coal-producing region about twice the size of Germany.
Abramovich has said he will continue to invest in Chukotka despite resigning as governor. Abramovich's spokesman, John Mann, said Thursday that the businessman had several projects in the region and the search for new investors was also under way.
According to a source in the local administration, Abramovich has invested some $2 billion in the region to develop infrastructure and provide aid to the inhabitants.
Media reported earlier that Abramovich, who mainly resides in London, had been keen to resign since at least 2006, when then-President Vladimir Putin, who highly valued Abramovich's work to improve living standards in the region, insisted he stay.
The newly inaugurated governor has pledged that he has no plans for a government reshuffle, saying: "I believe that the core team will stay."
Kopin stressed the importance of developing local infrastructure, including the construction of roads, power lines and airports. He said he hoped that considerable federal funding would be poured into Chukotka after the approval of the region's development strategy up to 2020.
Chukotka, the most northeasterly Russian region, with a population of just over 55,000, has large reserves of oil, natural gas, coal, gold and tungsten. The majority of the population lives on reindeer herding, hunting and fishing.
