He was probably educated at Trinity College, Cambridge, and on leaving the university is supposed to have joined the Middle Temple. He became a member of Gray's Inn in 1555. He has been identified without much show of evidence with a lawyer named Gastone who was in prison in 1548 under very discreditable circumstances. There is no doubt that his escapades were notorious, and that he was imprisoned for debt. George Whetstone says that Sir John Gascoigne disinherited his son on account of his follies, but by his own account he was obliged to sell his patrimony to pay the debts contracted at court. He was M.P. for Bedford in 1557-1558 and 1558—1559, but when he presented himself in 1572 for election at Midhurst he was refused on the charges of being "a defamed person and noted for manslaughter," "a common Rymer and a deviser of slaunderous Pasquelles," "a notorious rufilanne," and a constantly indebted atheist.

His poems, with the exception of some commendatory verses, were not published before 1572, but they may have circulated in manuscript before that date. He tells us that his friends at Gray's Inn importuned him to write on Latin themes set by them, and there two of his plays were acted. He repaired his fortunes by marrying the wealthy widow of William Breton, thus becoming stepfather to the poet, Nicholas Breton. In 1568 an inquiry into the disposition of William Breton's property with a view to the protection of the children's rights was instituted before the Lord Mayor, but the matter was probably settled in a friendly manner, for Gascoigne continued to hold the Walthamstow estate, which he had from his wife, until his death.

Gascoigne is the translator-of-record for two comedies, Ariosto's Supposes and Euripides Jocasta, which were performed in 1566 at Grays Inn, the most aristocratic of the renaissance London Inns of Court.

Gascoigne's most well known and controversial work was originally published in 1573 under the title A Hundredth Sundry Flowres bound up in one small Posie. Gathered partly (by translation) in the fyne outlandish Gardens of Euripides, Ovid, Petrarch, Aristotle and others; and partly by Invention out of our owne fruitfull Orchardes in Englande, Yelding Sundrie Savours of tragical, comical and moral discourse, bothe pleasaunt and profitable, to the well-smelling name, by London printer Richarde Smith. The book purports to be an anthology of courtly poets, gathered and edited by Gascoigne and two other editors known only by the initials "H.W." and "G.T." The book's content is throughout suggestive of courtly scandal, and the aura of scandal is skillfully elaborated through the effective use of initials and posies -- Latin or English tags supposed to denote particular authors -- in place of the real names of actual or alleged authors.

For reasons that are still unclear, the book was republished, with certain additions and deletions, two years later under the alternative title, The Posies of George Gascoigne, Esquire. The new edition contains three new dedicatory epistles, signed by Gascoigne, which apologize for some offense that the original edition had caused and effect to transfer sole responsibility for the book's content to Gascoigne himself. Apparently, however, the apology did not work the required trick; records of the Stationers' Company reveal that this second edition was swiftly suppressed, with many copies being recalled and destroyed. To this day it is unclear whether the book was actually an anthology with contributions by many individuals, or whether it was entirely or largely the work of Gascoigne. In 1928 B.M. Ward, in the first modern reprint of the book, argued that at least some of the poems were written by the obscure court poet, Edward de Vere, 17th Earl of Oxford, who had been proposed in 1920 by J. Thomas Looney as the real author of the Shakespearean works. Specifically, Ward argued that 24 of the poems, those published under the posies "Meritum petere, grave" ("to seek merit is a weighty thing"), and "Ever or Never," were by Oxford, and that Oxford had contributed the editorial content supplied under the initials "G.T.".

He sailed through as a soldier of fortune to the Low Countries in 1572, and was driven by stress of weather to Brielle, which luckily for him had just fallen into the hands of the Dutch. He obtained a captain's commission, and took an active part in the campaigns of the next two years, during which he acquired a profound dislike of the Dutch, and a great admiration for William of Orange, who had personally intervened on his behalf in a quarrel with his colonel, and secured him against the suspicion caused by his clandestine visits to a lady at the Hague.

Taken prisoner after the evacuation of Valkenburg by the English troops, he was sent to England in the autumn of 1574. He dedicated to Lord Grey de Wilton the story of his adventures, The Fruites of Warres (printed in the edition of 1575) and Gascoigne's Voyage into Hollande. In 1575 he had a share in devising the masques, published in the next year as The Princely Pleasures at the Courte at Kenelworth, which celebrated the queen's visit to the Earl of Leicester. At Woodstock in 1575 he delivered a prose speech before Elizabeth, and presented her with the Pleasant Tale of Hemetes the Hermit in four languages.

Most of his works were actually published during the last years of his life, after his return from the wars. He died at Barnack, near Stamford, where he was the guest of George Whetstone, on October 7, 1577. George Whetstone wrote a long poem in honour of his friend, entitled "A Remembrance of the wel-imployed life and godly end of George Gaskoigne, Esquire."

Gascoigne's theory of metrical composition is explained in a short critical treatise, "Certayne Notes of Instruction concerning the making of verse or ryme in English, written at the request of Master Edouardo Donati," prefixed to his Posies (1575). He acknowledged Chaucer as his master, and differed from the earlier poets of the school of Surrey and Wyatt chiefly in the added smoothness and sweetness of his verse.