Wyatt's professed object was to experiment with the English tongue, to civilise it, to raise its powers to those of its neighbours. A significant amount of his literary output consists of translations and imitations of sonnets by the Italian poet Petrarch; he also wrote sonnets of his own. He took subject matter from Petrarch's sonnets, but his rhyme schemes make a significant departure. Petrarch's sonnets consist of an "octave", rhyming abba abba, followed, after a turn (volta) in the sense, by a "sestet" with various rhyme schemes. Wyatt employs the Petrarchan octave, but his most common sestet scheme is cddc ee. This marks the beginnings of an exclusively "English" contribution to sonnet structure, that is three quatrains and a closing couplet. 15 years after his death, the printer Richard Tottel included 97 poems attributed to Wyatt among the 271 poems in Tottel's Miscellany, Songs and Sonnets.
In addition to imitations of works by the classical writers Seneca and Horace, he experimented in stanza forms including the rondeau, epigrams, terza rima, ottava rima songs, satires and also with monorime, triplets with refrains, quatrains with different length of line and rhyme schemes, quatrains with codas, and the French forms of douzaine and treizaine. Wyatt introduced contemporaries to his poulter's measure form (Alexandrine couplets of twelve syllable iambic lines alternating with a fourteener, fourteen syllable line),  and is acknowledged a master of the iambic tetrameter.
While Wyatt's poetry reflects classical and Italian models, he also admired the work of Chaucer and his vocabulary reflects Chaucer's (for example, his use of Chaucer's word newfangleness, meaning fickle, in They flee from me that sometime did me seek). Many of his poems deal with the trials of romantic love, and the devotion of the suitor to an unavailable or cruel mistress. Others of his poems are scathing, satirical indictments of the hypocrisies and flat-out pandering required of courtiers ambitious to advance at the Tudor court.
Wyatt was one of the earliest poets of the English Renaissance. He was responsible for many innovations in English poetry and, alongside Henry Howard, Earl of Surrey, introduced the sonnet from Italy into England. His lyrics show tenderness of feeling and purity of diction. He is one of the originators of the convention in love poetry according to which the mistress is painted as hard-hearted and cruel.
The Egerton Manuscript, originally an album containing Wyatt's personal selection of his poems and translations, preserves 123 texts, partly in the poet's hand. Tottel's Miscellany (1557), the Elizabethan anthology which created Wyatt's posthumous reputation, ascribes 96 poems to him, (33 not extant in the Egerton Manuscript). These 156 poems can be ascribed to Wyatt with certainty, on the basis of objective evidence. Another 129 poems have been ascribed to Wyatt purely on the basis of subjective editorial judgment. They derive mostly from two Tudor manuscript anthologies, the Devonshire and Blage manuscripts. In his preface to Sir Thomas Wyatt, The Complete Poems, R A Rebholz comments, 'the problem of determining which poems Wyatt wrote is as yet unsolved'. However, as Richard Harrier's The Canon of Sir Thomas Wyatt's Poetry (1975) shows, the problem of determining which poems aren't Wyatt's is much simpler. Harrier examines the documentary evidence of the manuscripts (handwritings, organisation, etc.) and establishes that there is insufficient textual warrant for assigning any of these poems to Wyatt. The only basis for ascribing these poems to Wyatt resides in editorial evaluation of their style and poetic merits. Compared with the indubitable standard presented in Wyatt's 156 unquestionably ascribable poems, fewer than 30 of these 129 poems survive scrutiny. Most can be dismissed at once. Joost Daalder's 1975 edition of Wyatt presents 199 poems, including 25 misascriptions (mostly segregated as "Unascribed") and is missing a dozen poems likely to be Wyatt's.
Critical opinions of his work have varied widely. Thomas Warton, the 18th-century critic, considered Wyatt "confessedly an inferior" to his contemporary Henry Howard, and that Wyatt's "genius was of the moral and didactic species and be deemed the first polished English satirist". The 20th century saw an awakening in his popularity and a surge in critical attention. C. S. Lewis called him "the father of the Drab Age" (i.e. the unornate), from what Lewis calls the "golden" age of the 16th century, while others see his love poetry, with its complex use of literary conceits, as anticipating that of the metaphysical poets in the next century. More recently, the critic Patricia Thomson describes Wyatt as "the Father of English Poetry".