Antonov, who has been appointed to the role by Russian President Vladimir Putin and replaces long-time ambassador Sergey Kislyak, takes over at a time when tensions are at an all-time high over Russia's alleged interference in the 2016 USA presidential election.
Antonov takes the job at a time when U.S. -Russia relations are badly strained following the approval of a new wave of U.S. sanctions against Moscow and the Kremlin's decision to sharply cut the U.S. diplomatic personnel in Russian Federation.
Antonov, 62, has served as a deputy foreign minister since December.
The name of outgoing ambassador Kislyak has emerged in relation to several of Trump's associates as a special counsel and congressional panels investigate Russian meddling and possible ties with the Trump campaign.
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The Russian leader also signed a decree relieving Sergei Kislyak from his duties as Russian Ambassador to the United States and Russia's Permanent Observer to the Organization of American States in Washington.
The outgoing ambassador played a prominent role in the controversy over Russia's possible involvement and interference in last year's US presidential election.
The European Union added him two years ago to its list of officials who are subject to Ukraine-related sanctions, citing his involvement in supporting the deployment of Russian troops to Ukraine.
The embassy statement says the step is necessary "due to the Russian government-imposed cap on USA diplomatic personnel in Russia". Previously he served as a deputy defence minister. He has largely stayed out of the public eye since then. He said the US and Russian Federation must pool efforts in the fight against terrorism and work together to strengthen nuclear non-proliferation.