After returning to England, he requested for the protection of his uncle, Moses Kean, an entertainer, who introduced Kean to the study of Shakespeare. At the same time, Miss Charlotte Tidswell, an actress who had been especially kind to him since he was young, taught him the basics of acting.
When his uncle died, Miss Charlotte was responsible in looking after Kean, and he began studying the main characters of Shakespeare. Kean displayed the creativeness of his mind by acting in a very different way from John Philip Kemble, an actor for many Shakespearean characters. A Mrs Clarke adopted Kean for his talents and appearance, but he was upset about a visitor's comments and suddenly left her house and went back to Miss Charlotte.
At the young age of 14, Kean was hired to act as main characters for 20 nights in the York Theatre, acting as Hamlet, Hastings and Cato. While he was at Richardson's Theatre, a travelling theatre company, the news of his talents reached George III, who ordered him to be at Windsor Castle. Kean later joined Saunders's circus, where while performaning as a horse rider, he fell and broke both legs. The accident left swelling on his foot throughout his life.
Kean learned music from Charles Incledon, dancing from D’Egville, and fencing from Angelo.
In 1807, he had a chance to act in leading parts at the Belfast theatre with Sarah Siddons, who began by calling him "a horrid little man" and changed to saying that he "played very, very well," but that "there was too little of him to make a great actor" after seeing his abilities.
The next year, Kean joined Samuel Butler's provincial troupe and went on to marry Mary Chambers of Waterford, a leading actress, on 17 July. His wife gave birth to two sons, one of whom was actor Charles Kean.
For several years, Kean's career had little chances to grow. But in 1814, the committee of Drury Lane Theatre, which was about to go bankrupt, decided to give Kean a chance among the "experiments" they were making to gain more popularity. When the hope of his first appearance in London got higher, he was so nervous that he exclaimed, "If I succeed I shall go mad." As he was unable to pay for his elder son's medical treatment for some time, his son died the day after Kean signed the three-year Drury Lane contract.
His appearance at the Drury Lane Theatre on 26 January 1814 as Shylock left the audience enthusiastic. People recognised that Kean had brought self-respect and humanity to his role of the character. Jane Austen refered to his popularity in a letter she wrote to her sister, Cassandra, on 2 March 1814: "Places are secured at Drury
Lane for Saturday, but so great is the rage for seeing Kean that only a third and fourth row could be got".
Appearances in "Richard III", "Hamlet", "Othello", "Macbeth" and "King Lear" demonstrated his ability to control his range of emotions. His joy was so great that he himself said, "I could not feel the stage under me."
In 1817, Charles Bucke, a local playwright, submitted his play "The Italians, or; The Fatal Accusation" to Drury Lane, for which Kean was to play the main role. The play was well received by everyone until Kean said that his part was too small for him. Then, after a performance in February 1819 where Kean went to make a mess at the opening night of "Switzerland" by historical novelist Jane Porter, for whom Kean had had a personal dislike, Bucke pulled the play out of disrespect for Kean's actions.
After much persuasion to still perform the play by the theater staff, Mr. Bucke then later had it republished with a introduction concerning the incident, including parts of conversation between the involved parties, which was later questioned in two books, "The Assailant Assailed" and "A Defense of Edmund Kean, Esq." The result was embarassment on both sides and the play being performed anyway on 3 April 1819 to a terrible reception thanks to the dispute already surrounding the play and Kean's previous conduct.
On 29 November 1820, Kean appeared for the first time in New York City as Richard III. The success of his visit to America was unmistakable, although he fell into a annoying dispute with the news media. In 1821, Kean appeared in Boston with Mary Ann Duff in "The Distrest Mother", by Ambrose Philips, an adaptation of Racine's Andromaque. On 4 June 1821, he returned to England.
Kean was the first to fix the terrible ending to Shakespeare's "King Lear", which had been replaced on stage since 1681 by Nahum Tate's happy ending adaptation "The History of King Lear". Kean had previously acted as Tate's Lear, but told his wife that the London audience "have no notion of what I can do till they see me over the dead body of Cordelia." Kean played as Lear for a few performances. They were not well received, though one critic described his dying scene as "deeply affecting", and with regret, he changed back to Tate.
Kean's lifestyle disrupted his career. As a result of his relationship with Charlotte Cox, the wife of a London city council member, Kean was sued by Mr Cox for criminal conversation (adultery). Kean was ordered to pay £800 to Mr Cox by a jury that only discussed for just 10 minutes. "The Times" launched a violent attack on him. The decision in the criminal conversation case of Cox v. Kean on 17 January 1825 caused his wife to leave him, and caused him to have such bitter feeling that he was boo-ed and attacked with fruits when he re-appeared at Drury Lane and nearly decided to retire permanently into private life. For many years, he lived at Keydell House, Horndean.
The purpose of Kean's second visit to America in 1825 was due to the repeated abuse he suffered in England. Some cities showed him a spirit of charity; many audiences submitted him to insults and even violence. In Quebec City, he was amazed with the kindness of some Huron Indians who went to his performances. He was made an honorary (unofficial) chief of the tribe, receiving the name "Alanienouidet". Kean's last appearance in New York was on 5 December 1826 in "Richard III", playing the same role in which he first acted in America.
When Kean returned to England, he was received with favour in the end. However, his heavy reliance on the use of stimulants caused him his talents. Still, his great powers was successful during the moments of his creativity over the absolute ruin of his physical potential. His appearance in Paris was a failure due to being drunk.
His last appearance on the stage was at Covent Garden on 15 March 1833, when he played in "Othello. When saying "Villain, be sure," in scene 3 of act iii, Kean suddenly started crying in a stammered voice "O God, I am dying. Speak to them, Charles," fell unconscious into his son, Charles Kean's, arms. He died in Surrey in 1833, and is honoured in the Parish Church where there is a memorial tablet on the floor, marking his grave and a wall plaque originally on the outside but moved inside and heavily restored during restoration work in 1904. He is buried in the parish church of All Saints, in the village of Catherington, Hampshire. His last words were claimed to have been "dying is easy; comedy is hard." In Dublin, Gustavus Vaughan Brooke acted as William Tell after Kean's death.
As stated in the "Encyclopædia Britannica" Eleventh Edition, it was in the impression of the great creations of Shakespeare's fine mind that the varied beauty and magnificence of the acting of Kean were displayed in their highest form, although probably his most powerful character was Sir Giles Overreach in Philip Massinger’s "A New Way to Pay Old Debts", the effect of his first performance of which was such that the pit rose altogether, and even the actors and actresses themselves were defeated by the terrific dramatic illusion. His main disadvantage as an actor was his height. Coleridge said, "Seeing him act was like reading Shakespeare by flashes of lightning."