She was born as Janet Thomson at Carshill, Shotts parish, Lanarkshire in 1795, the daughter of a shoemaker (James Thomson) and Mary Thomson (née Brownlee). She was a descendant of John Whitelaw, the forfeited covenanter from Shotts. At the age of three her family moved to Hamilton, and then to Langloan, in the parish of Old Monkland, Lanarkshire at the age of seven. For a time her parents became farm labourers, and she span and worked at the tambour-frame. Her father at length settled down in business for himself as a shoemaker, and John Hamilton, one of his young workmen, married Janet in 1809 in High Street, Glasgow, when Janet was thirteen. They lived together at Langloan for about sixty years, and had a family of ten children, seven sons and three daughters, who she taught all to read, starting with the alphabet.  John Hamilton's sister (Margaret Hamilton) married Thomas Shanks, from this line of descendants Janet has many living great-great-great-grandnieces and nephews, some of whom are stilll being named after her.
Having learned to read as a girl, she became familiar with the Bible, with Shakespeare and Milton, with many standard histories, biographies, and essays, and with the poems of Allan Ramsay, Robert Fergusson and Robert Burns. Before she was twenty years old she had written numerous verses on religious themes, but family cares prevented further composition until she was about fifty-four. Then she began to write essays for a supplement to Cassell's Working Man's Friend, as well as poems in English and Scots and reminiscences of village and rural Scotland during her youth.
During the last 18 years of her life she was blind, and her husband and one of her daughters (Marion) read to her. A son, James, served as her amanuensis. She died on 27 October 1873, aged 78, having never been "more than twenty miles from her dwelling". A large crowd of people attended her funeral, and a memorial fountain has been placed nearly opposite her cottage. She was buried in Old Monklands Cemetery in Coatbridge on 30 October 1873. On her tombstone are the words "She being dead yet speaketh".
- Poems and essays of a miscellaneous character on subjects of general interest. 1863 Glasgow
- Poems of purpose and sketches in prose of Scottish peasant life and character in auld lang syne, sketches of local scenes and characters : with a glossary 1865. Glasgow.
- Poems and Ballads. With introductory papers by G. Gilfillan and A. Wallace. 1868. Glasgow
- Poems, essays, and sketches. 1870. Glasgow A compilation of the best of the 1863 and 1865 poetry books.
- Pictures in Prose and Verse; or, Personal recollections of the late Janet Hamilton .. together with several hitherto unpublished poetic pieces. 1877. Edited by John Young. Glasgow.
This article incorporates text from a publication now in the public domain: Bayne, Thomas Wilson (1890). "Hamilton, Janet". In Stephen, Leslie; Lee, Sidney. Dictionary of National Biography. 24. London: Smith, Elder & Co.
- Pictures in Prose and Verse; or, Personal recollections of the late Janet Hamilton .. together with several hitherto unpublished poetic pieces. 1877. Glasgow. Pages 1–41
- Poems, sketches and essays. 1880. Glasgow. Introduction to Janet Hamilton's life and character by Rev. George Gilfillan.
- Janet Hamilton. and other papers. By Joseph Wright. 1889 Edinburgh
- Wilson, James Grant. Poets and Poetry of Scotland. Volume 2 1876 Pages 149-151.
- Murdoch, Alexander G. Recent and Living Scottish Poets. 1883 Pages 334-337.
- Eyre-Todd, George. Glasgow poets. 1903 Pages 224-233.
- Edwards, D. H. One Hundred Modern Scottish Poets. 1880 Pages 248-259
- Boos, Florence S., ed. Working-Class Women Poets in Victorian Britain: An Anthology. Broadview Press, 2008. This contains a selection of Hamilton poems in Scots and English with glosses and biographical materials.