He began acting at an early age, and followed his father into theatrical management. In 1727, Alexander Pope satirized Theophilus Cibber in his Dunciad as a youth who "thrusts his person full into your face" (III 132). On the stage, he was famous for playing Pistol in Henry IV, Part 2, and some of the comic roles his father had played when younger, but unsympathetic critics accused him of overemphasis. His private life later led Theophilus into bad reputation and scandal. He died in a shipwreck while bound for Ireland and a season in Dublin.
Theophilus Cibber was born during the Great Storm of 1703 and began acting in the Drury Lane Theatre at the age of 16 in 1721. As a young man, Cibber was a notorious rake, and associated with young men of a similar mind and reputation, such as the Duke of Wharton.
As the son of Colley Cibber, one of the theatre's managers, Theophilus became involved in the management of Drury Lane. In 1723, he became manager of the summer season, and in 1727 became assistant manager during the regular season. In 1732, one of the managers, Barton Booth, sold his share to John Highmore, and another of the managers, Robert Wilks, fell ill and died. Cibber senior became disenchanted by the involvement of Wilks' widow, through her representative John Ellys, in the management of the company. He dropped out of the management and leased his share in the company to his son. Cibber junior took the lead in the management of the theatre during the 1732–33 season, until he fell ill. The actions of Ellys and Highmore in his absence, which appear to have been largely centred on saving or making money, irritated Theophilus and friction grew between them. The other managers approached Cibber senior and offered to buy out his share. Without consulting Theophilus, Colley Cibber sold them his share for 3,000 guineas, and they promptly gave Theophilus his notice. Theophilus led the actors in a walkout and they set themselves up as rival, but informal, company of players in the Haymarket. The Cibbers applied for a letters patent to perform at the Haymarket, but it was refused, and the Drury Lane managers attempted to shut down Cibber by conspiring in the arrest of his leading actor, John Harper, on a charge of vagrancy. Public opinion swung to Theophilus' side, and Harper was released. The Drury Lane managers were defeated, and Theophilus regained control of the company on his own terms.
Theophilus married actress Jane Johnson and they had four children: Colley George in 1726, Catherine in 1727, Jane in 1729, and Elizabeth in 1732. Colley George and Catherine died in infancy, and their mother died at the age of 26 just after the birth of Elizabeth from puerperal fever. Jane and Elizabeth were raised in the house of their grandfather, Colley Cibber.
Two years after the death of his first wife, Jane, Cibber married the singer and actress Susannah Maria Arne, the sister of musician Thomas Arne on 21 April 1734. Unusually, Susannah Maria insisted on a prenuptial agreement that protected her own property and income by placing it in the hands of two trustees, who released it to her in small amounts. Theophilus had no access to the money, and the agreement stipulated that if she died without children, then the money was to be inherited by her parents rather than her husband. They had two children, Susannah in 1735 and Caius-Gabriel in 1736, but they both died aged less than a year.