The official spokesperson in the Ministry of External Affairs said that Rao would take up her assignments shortly before India and US holds its second strategic talks.
Vishnu Prakash, the spokesperson of the external affairs ministry, tweeted Rao's appointment as India's next envoy to Washington on the social networking site.
Rao has played key positions and had been India's envoy to various foreign countries, including China and Sri Lanka. She has also been the only women spokesperson in the MEA. She had earlier served in Washington as a junior diplomat.
Rao's appointment was cleared by the government a few weeks ago. Her tenure as foreign secretary ends July 31. She will succeed Meera Shankar to become India's second woman ambassador to the US.