See E. J. Gorn, The Manly Art: Bare-Knuckle Prize Fighting in America (1986).
He was educated at the City of London School from 1841–45, and started life as a clerk in a wine merchant's office. In 1854, Toole married Susan Hale (née Caslake), a widow five years older than he. They had a son, Frank Lawrence, and a daughter, Florence Mabel, but both children died in their 20s.
In 1854, Toole made his first professional appearance in London at the St. James's Theatre, acting as Samuel Pepys in The King's Rival, by Tom Taylor and Charles Reade, and Weazel in My Friend the Major by Selby. He returned to the provinces, but by 1856 was engaged in London at the Lyceum Theatre, including as Fanfaronade in Belphegor at the Lyceum Theatre (in which Marie Wilton, made her first London appearance). Thereafter, he frequently performed with Wilton. In 1857, having had a great success in London as Paul Pry in John Poole's farce of that name, he made his first of many successful provincial summer tours. During this first tour, he met and acted together with Henry Irving, and the two remained close friends over their long careers. In 1858, he scored a notable hit creating the role of Tom Cranky in John Hollingshead's farce The Birthplace of Podgers.
Toole was then engaged in 1868 at the Gaiety Theatre by Hollingshead, appearing in many pieces there including Thespis, the first Gilbert and Sullivan collaboration. In 1873–74, among other successes, he portrayed the Irishman Brulgruddery in John Bull by the younger Colman; Bob Acres in The Rivals by Richard Brinsley Sheridan, together with Charles James Mathews and Samuel Phelps; and created the role of the barrister Hammond Coote in Wig and Gown by James Albery. Toole's fame was at its height in 1874, when he went on tour to America, but he failed to reproduce there the success he had found in England. He remained based mostly at the Gaiety until the end of 1877, when he moved to the Globe Theatre under his own management for two years.
In 1878, Toole created the role of Charles Liquorpond in A Fool and his Money by H. J. Byron. Liquorpond was a retired footman unexpectedly overtaken by wealth, and Toole's affectedly superior pronunciation, particularly of his own name, was a tremendous success. In his prime, Toole achieved wide popularity as a comic actor, being noted for his comic delivery of words, but he did not confine himself exclusively to comedy. He also excelled in domestic melodramas (adaptations by Dion Boucicault and others of Charles Dickens and similar writers), playing "tender-hearted victims of fate", where he was famously able to combine humour and pathos. The Times said of his performance in Dearer than Life by Henry James Byron, "Mr. J. L. Toole... is associated in the minds of the general public mainly with parts provoking to uproarious laughter; but it may fairly be questioned whether, like his predecessor in this also, his heart does not lie with, and he himself is not seen to more advantage in, the telling sketches from everyday life to which, for want of a better, we give the name of domestic drama. Anything more lifelike than the intensity of cold and hunger from which he may be almost said to suffer, in the garret-scene, as Michael Garner it would be difficult to conceive.
In 1879, Toole realized a lifelong ambition by taking over the management of the Folly Theatre in London. This triumph was offset by the death of his son in the same year, after a football injury. He renamed the theatre "Toole's Theatre" in 1882, becoming the first actor to have a West End theatre named after him. He was often away in the provinces, but he produced here a number of plays:
Toole began to be troubled by gout in 1886. After his daughter died in 1888, followed by his wife in 1889, Toole was disconsolate, and his health deteriorated further. Nevertheless, he toured Australia and New Zealand in 1890. After this, his stage appearances gradually became fewer. The gout left him sometimes unable to walk, and after an 1893 illness during Thoroughbred by Ralph Lumley, he retired from the London stage, although he made occasional appearances in the provinces until about 1896. His theatre was demolished in 1895 for an extension of Charing Cross Hospital, and he dissolved his theatre company after an 1896 tour.
The critic Clement Scott called him "one of the kindest and most genial men who ever drew breath.... No one acted with more spirit or enjoyed so thoroughly the mere pleasure of acting." Toole's genial and sympathetic nature was conspicuous off the stage as well as on it, and he was known as a great practical joker. He published his reminiscences in 1888.
Ultimately he retired to Brighton, where after a long struggle with Bright's disease and a degenerative spinal illness, he died at the age of 76. He is buried at Kensal Green cemetery in London, next to his wife and children. Toole was a good businessman and left a considerable fortune of over £81,000, out of which he made a number of bequests to charity, to needy actors and to his friends.