In a diplomatic career spanning 38 years, he served as the Indian ambassador to Australia, Afghanistan, Iran, and Saudi Arabia.

Though his ancestral home is in the city of Yusufpur, Ghazipur, of the Uttar Pradesh state, he spent his formative years in Kolkata.

[8] His deputy T. P. Sreenivasan wrote that while Ansari's stint as the permanent representative, he refuted Pakistan's allegations of human rights abuses in Jammu and Kashmir by "the horns and subdued it whenever necessary".

He also wrote that appointing Ansari for this post at a time when "Pakistan went all out to bring Kashmir to the centre of international attention after the end of the Cold War" showed India's secular credentials.

[13] After leaving the post in 2002, he served as a visiting professor of the Academy for Third World Studies Department of the Jamia Milia Islamia from 2003 to 2005.

[14] In June 2007, Ansari, in his capacity as NCM chairman, upheld the decision of St. Stephen's Delhi to earmark a small percentage of seats for Dalit Christians.

[17] The NDA cited Ansari's conduct in the Rajya Sabha during The Lokpal Bill, 2011 debate when he had abruptly adjourned the House sine die.

[18] Hamid Ansari was re-elected for the second term on 7 August 2012, defeating the NDA's nominee Jaswant Singh by a margin of 252 votes.

Ansari is a West Asia scholar and has written on the Palestinian issue and taken positions inconvenient to the Indian official line on Iraq and Iran.

[21] He was the chairman of a working group on "Confidence building measures across segments of society in the State," established by the Second Round Table Conference of the Prime Minister on Jammu and Kashmir in 2006.