In addition to raising three children and several foster children, Irene began her career as a high school teacher.

At 23, she left the security of a government job for the uncertain life of an activist, working for various labor and rights groups, including the Young Christian Workers Movement (YCM), based in Brussels.

In 1970, Irene gave up her teaching career to become a full-time organiser for young workers. She became national president of the Malaysian YCW from 1972-1975 and was a member of the international committee from 1973-1975.

During that time, she was able to organise the first textile workers union and began programmes to create trade unions and improve consumer education. She also focused on the development of women leaders in the labour movement.

In 1976, Irene joined the Consumers Association of Penang (CAP) and worked on consumer education, launching consumer clubs for secondary school children to teach them about basic needs, safety and protection of the environment. She also began a consumer programme for rural women, linked to a breast-feeding campaign and the Nestlé boycott.

Irene became involved with several women’s rights campaigns, and helped, through her work with those organisations, to pass certain laws relating to violence against women.

Various women's groups were birthed as a result of these campaigns. One was the All Women's Action Society, of which Fernandez was president for five years. It is now one of the strongest women's advocacy groups in Malaysia.

The Domestic Violence Act, Sexual Harassment Code and changes to the laws related to rape are all a result of its work.

That same year, she was the founding member of Asia Pacific Women Law and Development (APWLD). This regional organisation was designed to bring together female lawyers and activists to look at law affecting women across the Far East. She was director for more than 10 years.

During the early 1990s, Irene was working very closely with women workers in the plantation and electronics sector. Later on, Irene got more involved with anti-trafficking work.

In 1991, Irene formed Tenaganita in Kuala Lumpur – with the mission to protect and promote the rights for migrants, refugees, and trafficked women and children.

From 1992, Irene was the chair of the Pesticide Action Network, working for the elimination of pesticides and developing sustainable agriculture, which led to campaigns on health, against GMOs, and taking back control of seeds.

In her years of work, Irene was harassed repeatedly by certain parties for her activism.

In 1995, Tenaganita published a report on the abuse of migrant workers, cataloguing the malnutrition, physical and sexual abuse and the appalling conditions the workers endure, and setting out the facts about the detention camps where physical violence is law. The research included interviews with as many as 300 migrant workers.

As a result of the publication, the Malaysian government was forced to admit that 46 people indeed had died of various medical conditions in their detention centres.

In March 1996, Irene was arrested at her home and convicted under the Printing Presses and Publications Act of 1984 with "maliciously publishing false news.

Her trial became the longest in Malaysian history and many of the witnesses she was relying on were deported, preventing her from making her defense. Her criminal trial dragged on for seven years.

Stanley Augustin, the prosecutor, accused her of blackening her country’s reputation. “The court must take into account the interests of the nation,” he said. “Freedom of the press is not freedom to say anything you like. It must be confined and cannot hurt the public or national interest.”

In 2003, she was found guilty and sentenced to a year in prison, having by then appeared in court more than 300 times. By 2005, she was still on bail pending an appeal. While on bail, her passport was confiscated and the government used her conviction to bar her from running for parliament in the 2004 Malaysian elections. On 24 November 2008, Justice Mohd Apandi Ali overturned her earlier conviction and acquitted her, ending the thirteen-year case.

Despite harassment and intimidation, Irene courageously refused to allow the situation limit her work or blunt her message – even when the prison term hung over her head. She never used or advocated violence and have always worked in an open and legal way.

Convinced that she had been targeted for her legitimate work as a human rights defender, Amnesty International campaigned continuously for her acquittal and supported her throughout her trial. During her trial, she told The Los Angeles Times that she was ready for jail. "It will give me an opportunity to write a report on jail conditions and see what changes need to be made,” she said.

Irene never lost her zeal for battle.

Irene left us on 31 March 2014 at the age of 67, due to a heart failure.