"I'm confident that his experience and diplomatic acumen will be an asset as we work to strengthen cooperation and build a constructive relationship with Russia", Pompeo wrote on Twitter.
The US Senate voted on Thursday to confirm the nomination. Sullivan, who prior to his appointment served as deputy secretary of state, replaces Jon Huntsman, who completed his tenure in Moscow in October.
Speaking on Tuesday during his visit to the United States, Russian Foreign Minister Sergey Lavrov praised Sullivan as a very highly professional diplomat and said that Moscow would be happy to cooperate with him.
President Donald Trump announced his decision to nominate Sullivan for the post on 11 October.
Sullivan used to be in charge of counterterrorism negotiations in Russia as the State Department official. Sullivan pledged late in October to support dialogue with Russia on arms control, terrorism fight, denuclearisation of the Korean Peninsula, and conflicts in Syria and Afghanistan.