She was the daughter of Carel Eduard Mercier, a commission agent, and Francijntje Fonger, members of the liberal Dutch Reformed Church.

In it she drew the attention of parents to the fact that their daughters were brought up to be 'fluff and waste of time' and that they, especially unmarried women, were condemned to a purposeless life.

In her book Verbonden Schakels (Linked Shackles), she published a collection of articles that for the most part had appeared between 1878 and 1888 in the magazines Vragen des Tijds and, later, Sociaal Weekblad.

Instead of revolutionary upheaval, she advocated a gradual transformation of society, not through charity but by encouraging workers to practice "self-help".

She studied many topics and wrote in Eigen Haard and in the Sociaal Weekblad, which had been founded by Kerdijk in 1887, on such diverse subjects as the nutritional status of the working class; housing issues; labour in factories; workers' clubs in America; production cooperatives in France; the work of Arnold Toynbee; the ideas of state socialism of Edward Bellamy, as published in his popular book, Looking Backward, 2000–1887; the reforming work of Samuel Augustus Barnett and his wife Henrietta Octavia Weston Rowland; the results of a labour survey of 1890; and a survey of workers' budgets.

Mercier obtained income from translation and correction work for the Algemeen Nederlandsch Werklieden-Verbond (ANWV), one of the first Dutch trade union federations.

As founder or co-founder of several institutions, she created a field of work for women of her class and at the same time contributed to the improvement of social conditions.

In 1887 she established the first community kitchen in the Amsterdam Jordaan district, financed by sugar refiner Willem Spakler.

[1][2] Mercier is mainly remembered as the person who made the public aware of the slums of Amsterdam, which were largely the consequence of the Industrial Revolution and its need for factory workers.

After a tour of the Amsterdam Jordaan and other working-class neighbourhoods, led by the doctor and suffragist, Aletta Jacobs, she wrote a series of articles about housing for workers.

The importance that Mercier attached to good housing as a way of improving the condition of the working class was apparent from her share in the founding of the company, N.V. Bouwonderneming Jordaan, in 1896.

With money from the philanthropist Peter Wilhelm Janssen, 131 slums in the Jordaan were bought, converted into good working-class houses and placed under the supervision of the social worker, Louise Went.

Mercier was closely involved in the content of the lessons, courses, lectures and clubs that Ons Huis offered and which were intended for children, women and men.

The initiative for this came from Marie Muller-Lulofs, who was inspired by Mercier's article On the threshold of social life, which had been published in 1885.