A Charles Hart was christened on 11 December 1625, in the parish of St. Giles Cripplegate, in London. It is not absolutely certain that this was the actor, though the name was not common at the time. Hart began his career as a boy player with the King's Men; he was an apprentice of Richard Robinson, longtime member of that company. Hart established his reputation by playing the role of the Duchess in The Cardinal, the tragedy by James Shirley, in 1641. He served as a soldier in the English Civil War, and was an officer in Prince Rupert's regiment of cavalry, along with fellow actors Nicholas Burt and Robert Shatterell. Hart and the others most likely saw combat at the battles of Marston Moor and Nasby, and perhaps at Edgehill as well.
Hart then returned to acting; evidence suggests he was with other displaced English actors in Europe in 1646. In 1648, Hart, Walter Clun and eight other actors, were involved in an attempt to re-start the King's Men company during the Puritan Commonwealth, which, perhaps unsurprisingly, did not succeed. On 5 February 1648, at the Cockpit Theatre, Hart and other King's Men were arrested for violating the ban against theatrical performance; they were caught in the midst of a performance of Rollo Duke of Normandy (in which Hart played the character Otto). Hart and the others were imprisoned for a short time, then released.
Just before the Restoration of the monarchy in 1660, acting resumed on a larger scale, and Hart seems to have been then a member of a company performing at the Cockpit playhouse, led by Michael Mohun. As soon as the King's Company was formed in 1660, Hart became one of its leading men; he specialized in playing the male half of witty, bantering couples. This type of dialogue in Restoration comedy was largely influenced by the talents and personalities of Hart and Nell Gwyn, in plays like James Howard's The Mad Couple; Gwyn was his mistress before she became Charles II's. Hart's natural dignity in playing royal roles was also often commented on by contemporaries, and in the heroic play he "was celebrated for superman roles, notably the arrogant, bloodthirsty Almanzor in John Dryden's Conquest of Granada.
When Hart played in Euterpe Restored in 1672, Richard Flecknoe composed the following lines:
Throughout his Restoration career, Hart filled a range of noteworthy parts. He was Cassio in early stagings of Shakespear's Othello; after 1669 he played the title role. He played roles in revivals of plays by Shakespeare, Ben Jonson, and John Fletcher —
— and in contemporary dramas, by John Dryden —
— and by other dramatists —
In 1682, when the King's Company joined with the Duke's Company to form the United Company, Hart retired due to poor wealth, with a pension of 40 shillings per week. The well-known story that Hart was the illegitimate grandson of Shakespeare's sister Joan is largely discredited.