Fielding was born at Sharpham, Somerset, and educated at Eton College, where he established a lifelong friendship with William Pitt the Elder. When Henry was 11, his mother died. A suit for custody was brought by his grandmother against his charming but irresponsible father, Lt. Gen. Edmund Fielding. The settlement placed Henry in his grandmother's care, although he continued to see his father in London. In 1725, Henry tried to abduct his cousin, Sarah Andrews, while she was on her way to church. To avoid prosecution, he fled. In 1728, he travelled to Leiden to study classics and law at the university. However, lack of money obliged him to return to London and he began writing for the theatre. Some of his work was savagely critical of the government of Prime Minister Sir Robert Walpole.
The Theatrical Licensing Act of 1737 is alleged to be a direct response to his activities. The particular play that triggered the Licensing Act was the unproduced, anonymously authored, The Golden Rump, but Fielding's dramatic satires had set the tone. Once the act was passed, political satire on the stage became virtually impossible, and playwrights whose works were staged were viewed as suspect. Fielding therefore retired from the theatre and resumed his career in law in order to support his wife Charlotte Craddock and two children, by becoming a barrister.
Fielding's lack of financial acumen meant he and his family often endured periods of poverty, but he was helped by Ralph Allen, a wealthy benefactor, on whom Squire Allworthy in Tom Jones was later based. Allen went on to provide for the education and support of Fielding's children after the writer's death.
Fielding never stopped writing political satire and satires of current arts and letters. The Tragedy of Tragedies (for which Hogarth designed the frontispiece) was, for example, quite successful as a printed play. He also contributed a number of works to journals of the day.
From 1734 until 1739 he wrote anonymously for the leading Tory periodical, The Craftsman, against the Prime Minister, Sir Robert Walpole. Fielding's patron was the opposition Whig MP (and his boyhood friend from Eton) George Lyttelton. Lyttelton followed his leader Lord Cobham in forming a Whig opposition to Walpole's government, called the Cobhamites (who also included Fielding's other Eton friend, William Pitt). In the Craftsman, Fielding articulated the opposition's attack on bribery and corruption in British politics. Although writing for the opposition to Walpole that included Tories as well as Whigs, Fielding was "unshakably a Whig" and often praised Whig heroes such as the Duke of Marlborough and Gilbert Burnet.
Fielding dedicated his play Don Quixote in England to the opposition Whig leader Lord Chesterfield and it was published on 17 April 1734, the same day writs were issued for the general election. He dedicated his 1735 play The Universal Gallant to Charles Spencer, 3rd Duke of Marlborough, a political follower of Chesterfield. The other prominent opposition newspaper, Common Sense, was named after a character in Fielding's Pasquin (1736) and was founded by Chesterfield and Lyttelton. Fielding wrote at least two articles it in 1737 and 1738.