He is thought to have been connected with the family of Henderson of Fordell, but there is no clear evidence. He is described, on the title-page of the 1570 edition of his Fables, as "scholemaister of Dunfermeling," probably of the grammar-school of the Benedictine Dunfermline Abbey. There is no record of his having studied at St Andrews, the only Scottish university at this time; but in 1462 a "Master Robert Henryson" is named among those incorporated in the recently founded University of Glasgow. It is therefore likely that his first studies were completed abroad, at Paris or Louvain. He must have been in lower orders, if, in addition to being master of the grammar school, he is the notary Robert Henryson who subscribes certain deeds in 1478. As William Dunbar refers to him as deceased in his Lament for the Makaris, his death may be dated about 1500. Efforts to draw up a chronology of his poems are mere guess-work.
Henryson's longest, and in many respects his most original and effective work, is his Morall Fabillis of Esope, a collection of thirteen fables, chiefly based on the versions of Anonymus, John Lydgate and William Caxton. The outstanding merit of the work is its freshness of treatment. The work is unrivalled in English fabulistic literature. The earliest available texts are the Chartens text printed by Lekpreuik in Edinburgh in 1570 and the Harleian Manuscript No. 3865 in the British Museum.
In the Testament of Cresseid, Henryson supplements Geoffrey Chaucer's tale of Troilus with the story of the tragedy of Cresseid. Here again his literary craftsmanship saves him from the disaster which must have overcome another poet in undertaking to continue the part of the story which Chaucer had intentionally left untold. The description of Cresseid's leprosy, of her meeting with Troilus, of his sorrow and charity, and of her death, give the poem a high place in writings of this genre.
The poem entitled Orpheus and Eurydice, which is drawn from Boethius, contains some good passages, especially the lyrical lament of Orpheus, with the refrains "Quhar art thow gane, my luf Erudices?" and "My lady quene and luf, Erüdices." It is followed by a long moralitas, in the manner of the Fables.
Thirteen shorter poems have been ascribed to Henryson. Of these the pastoral dialogue "Robene and Makyne," perhaps the best known of his work, is the most successful. Its model may perhaps be found in the pastourailes, but it stands safely on its own merits. Unlike most of the minor poems it is independent of Chaucerian tradition. The other pieces deal with the conventional 15th century topics, Age: Death, Hasty Credence, Want of Wise Men and the like. The verses entitled "Sum Practysis of Medecyne," in which some have failed to see Henryson's hand, is an example of that boisterous alliterative burlesque which is represented by a single specimen in the work of the greatest makers, Dunbar, Douglas and Lyndsay. For this reason, if not for others, the difference of its manner is no argument against its authenticity.
The manuscript authorities for the text are the Asloan, Bannatyne, Maitland Folio, Makculloch, Gray and Riddell. Chepman and Myllar's Prints (1508) have preserved two of the minor poems and a fragment of Orpheus and Eurydice. The first complete edition was prepared by David Laing (1 vol., Edinburgh, 1865).