Illingworth was born at Bradford, Yorkshire, the son of Daniel Illingworth and his wife Elizabeth Hill. He was educated at Huddersfield College and entered the family worsted spinning business of D Illingworth & Sons at the age of 16. In 1865, with his brother Henry, he established the Whetley Mills, one of the largest factories in Bradford. He was also a director of the Bradford District Bank. He had strong non-conformist and free trade views and entered into politics.
At the 1868 general election, Illingworth was elected MP for Knaresborough, but lost the seat in 1874. He was then elected at Bradford at the 1880 general election until the constituency was reorganised under the Redistribution of Seats Act 1885. At the 1885 general election he was elected for Bradford West and held the seat until 1895.
Illingworth married Margaret Holden, daughter of Sir Isaac Holden, 1st Baronet in 1863 and his brother Henry married another daughter of Holden creating a strong alliance of two of the dominant Bradford families of the time. Henry was the father of Percy Illingworth and Albert Illingworth who were also active in politics in Yorkshire.
- Debretts House of Commons and the Judicial Bench 1886
- "Bradford Libraries - Alfred Illingworth". Archived from the original on 6 January 2009. Retrieved 14 January 2009.
- Leigh Rayment's Historical List of MPs – Constituencies beginning with "K" (part 2)
- Leigh Rayment's Historical List of MPs – Constituencies beginning with "B" (part 4)
- "Court Circular". The Times (36908). London. 25 October 1902. p. 8.
- Hansard 1803–2005: contributions in Parliament by Alfred Illingworth
|Parliament of the United Kingdom|
Basil Thomas Woodd
and Isaac Holden
| Member of Parliament for Knaresborough
Basil Thomas Woodd
Henry William Ripley and
William Edward Forster
| Member of Parliament for Bradford
With: William Edward Forster
|New constituency|| Member of Parliament for Bradford West