Jahangir has spent her career defending the human rights of women, religious minorities, and children of Pakistan. She has been and remains a staunch critic of the Hudood ordinance and blasphemy laws of Pakistan put in place as part of General Muhammad Zia-ul-Haq's Islamization program in Pakistan.  Her willingness to relentlessly defend victims of rape, women seeking divorce from abusive husbands, people accused of blasphemy, her work on the issues of child labor, and her continuous criticism of political parties has made her one of the most controversial figures in Pakistan.

Jahangir became involved in protests at a very young age and launched her first legal battle in 1972 at the age of 20 when she was not even a lawyer. (She did not complete her law degree until 1978). When her father was detained by Zulfikar Ali Bhutto, then Prime Minister of Pakistan and no one dared to represent him, she filed a constitutional petition in the Supreme Court not only challenging his arrest, but even questioning whether the Bhutto government had come to power legally. In a landmark judgment ten years later she won her case.

In 1980, Jahangir and her sister, Hina Jilani, got together with fellow activists and lawyers to form the first law firm established by women in Pakistan. They also helped form the Women's Action Forum (WAF) that same year. The first WAF demonstration was in 1983, when some 25-50 women took to the streets protesting the Safia Bibi case. Safia, a young blind girl, had been raped, yet ended up in jail on the charge of zina (fornication). In 1986 Jahangir and Hina set up AGHS Legal Aid, the first free legal aid centre in Pakistan. The AGHS Legal Aid Cell in Lahore also runs a shelter for women, called 'Dastak'.