Ryan Tully has resigned from his post as Senior Director for European and Russian Affairs at the National Security Council in the wake of the riots at the Capitol, Jennifer Jacobs, White House correspondent for Bloomberg, said.
Other senior NSC officials are also expected to step down soon, Reuters reported, citing a senior administration official.
Earlier in the day, US special envoy to Northern Ireland, Mick Mulvaney, announced his resignation.
John Costello, deputy assistant secretary for intelligence and security at the Department of Commerce, also resigned, explaining his position on Twitter.
Transportation Secretary Elaine Chao has also resigned, according to a statement.
Among other officials to have decided to step down after violent riots at the Capitol, was Deputy National Security Adviser Matthew Pottinger who, according to Bloomberg, said he is among a number of officials "dismayed" by the siege and "Trump's role in inciting violence".
White House Deputy Press Secretary, Sarah Matthews, announced her resignation on Wednesday, saying she will be stepping down immediately.
According to media reports, Deputy chief of staff Chris Liddell is also considering leaving his post.
Justice Department Civil Rights Division Chief, Eric Dreiband, will resign effective Friday, according to a statement obtained by Reuters.
US Treasury Secretary Steven Mnuchin is expected to serve out his term until Biden's inauguration on 20 January, the agency reported, citing sources familiar with the matter.
A string of resignations comes shortly after a Congress session officially to confirm Democrat Joe Biden's presidential win was disrupted on Wednesday by crowds of aggressive pro-Trump supporters, who broke into the Capitol and caused damage to the building. At least four people were killed and dozens were injured during the unrest.