Jessie Fraser was born at Ecclesmachan, Linlithgow, Scotland, on 14 April 1867, the daughter of Janet Hearne and her husband, Walter Fraser, a ploughman. With her parents and three younger sisters, Jessie emigrated to New Zealand on the Canterbury, arriving at Lyttelton on 2 September 1874. A decade later the family had settled in Denniston, Westland, where Walter Fraser worked as a miner.
Aged 17, Jessie Fraser married John Barr Aitken, a coalminer, on 25 July 1884 at Buller. The couple, who were to have seven daughters and four sons, lived at Burnett's Face, near Denniston, until around 1902. By 1906 they were living at Kaitangata, a mining town near Balclutha. After the death of her husband in Nelson in 1907, Jessie Aitken moved to Wellington where she initially lived with her son Hugh. Here she became an active member of many women's organisations.
Aitken joined the Wellington Housewives' Union, established in 1912. The union campaigned against rising living costs, encouraged co-operative buying, and aimed to establish a political voice for women in the home. Housewives' unions were closely associated with the Social Democratic Party, and later the New Zealand Labour Party. Aitken belonged to the Wellington branch of the SDP, and in 1916 was elected to its executive and social committees.
During the First World War Aitken was a member of the Women's Anti-Conscription League, formed in Wellington in June 1916. Believing that participation in warfare was 'a matter of individual conscience', the league organised a large deputation of women to wait on Prime Minister William Massey. Aitken was a key speaker. She stated that 'as a mother she objected to the boys being compelled to go to war if they did not want to go.' The league's protest was greeted with anger and amusement by Massey; the Military Service Bill passed into law shortly afterwards.
From 1916 to 1918 Aitken was president of the newly formed Wellington branch of the Women's International League, which promoted international co-operation as an alternative to the 'outworn system of warfare'. As president, Jessie Aitken was involved in lobbying the government on the ill-treatment of conscientious objectors and providing practical support for their families. The league linked its objectives to the movement for women's rights, arguing that there would be no war if women were granted equal rights of citizenship.
Aitken was a strong advocate of a role for women in local and national politics. She was elected to the Wellington Hospital and Charitable Aid Board as a Labour candidate in April 1917, and with fellow members Alberta McLaren, Annie McVicar and Grace Neill she supported the enhancement of the welfare of women and children. Aitken was a member of the board's public health committee, responsible for hospital inspections; and the charitable aid committee, which dealt with appeals for assistance from needy families. After a South Island holiday in September 1918, Aitken returned to her most strenuous period of board membership during and after the November influenza epidemic. She was an active member of the board's social welfare committee, established in February 1919 to assist widows, widowers and orphans of the epidemic.
During this time Jessie Aitken remained active in the labour movement. She attended two New Zealand Labour Party conferences: as a delegate for the Women's International League in 1917, and for the Wellington Labour Representation Committee in 1918. On the latter occasion, Aitken supported increased state allowances for widows and an unsuccessful remit for the formal representation of women delegates at party conferences. An unprecedented six women delegates attended this conference; the following year none were present.
Wellington women Sarah Beck, Jane Donaldson and Sarah Snow were among Jessie Aitken's closest allies. Together they drew the political disabilities of women to the attention of the Labour Party and provided the leadership for many local progressive women's organisations. They urged Labour MPs to introduce legislation to allow women to stand as parliamentary candidates. In December 1918 James McCombs added the relevant clause to the Legislative Council Amendment Bill; although this was rejected, the Women's Parliamentary Rights Act was passed the following year.
Aitken was an unsuccessful Labour candidate in the April 1919 Wellington City Council elections. In a campaign speech at a meeting of the Wellington branch of the National Council of Women of New Zealand, she pledged to help improve housing conditions and sanitation, and provide rest rooms for women and recreational facilities for children. It was the first time women had stood for election to the Wellington City Council. In May 1919 Aitken attended the first New Zealand Town-planning Conference and Exhibition and was on the committee that discussed issues relating to women and children.
In 1920 Aitken resigned from the Labour Party and hospital board and moved to Melbourne, where she lived until around 1928. She died aged 66 at her daughter's home in Wellington on 18 January 1934. A committed feminist, socialist and peace worker, Jessie Aitken was one of a new generation of women who held public office.