Powys was born in Shirley, Derbyshire, in 1872, the son of the Reverend Charles Francis Powys (1843–1923), who was vicar of Montacute, Somerset for thirty-two years, and Mary Cowper Johnson, a descendent of the poet William Cowper. He came from a family of eleven children, many of whom were also talented. His two younger brothers Llewelyn Powys (1884–1939) and Theodore Francis Powys were well-known writers, while his sister Philippa published a novel and some poetry. Another sister Marian Powys was an authority on lace and lace-making and published a book on this subject. His brother A. R. Powys, was Secretary of the Society for the Protection of Ancient Buildings, and published a number of books on architectural subjects. John studied at Sherborne School and graduated from Corpus Christi College, Cambridge, June 1894.
On 6th April, 1896 he married Margaret Lyon. They had a son, Littleton Alfred, in 1902. The marriage was unsatisfactory and Powys eventually lived a large part of each year in the USA and had relationships with various women, before establishing a permanent common-law relationship with Phyllis Playter in the 1920s. However, he diligently supported Margaret and the education of their son. Another important woman in his life was the American poet Frances Gregg, whom he first met in Philadelphia in 1912. He was also a friend of the famous dancer Isadora Duncan. Another friend and an important supporter in America was the novelist Theodore Dreiser.
Powys's first employment was teaching in girls’ schools. He then worked as an Extension lecturer throughout England, for both Oxford and Cambridge Universities. Then in 1905 he began lecturing in the USA for The American Society for the Extension of University Teaching. He worked as an itinerant lecturer until the early 1930s, gaining a reputation as a charismatic speaker. However, he usually spent the Summer in England. During this time he travelled the length and breadth of the USA, as well as into Canada. He engaged in public debate with the philosopher Bertrand Russell on marriage, as well as with the philosopher and historian Will Durant; he was also a witness in the obscenity trial of James Joyce's novel, Ulysses, and was mentioned with approval in the autobiography of US feminist and anarchist, Emma Goldman. Powys would later share Goldman's support for the Spanish Revolution.
His first published works were highly derivative collections of poetry published in the 1890s. His first novel Wood and Stone, dedicated to Thomas Hardy, was published in 1915. This was followed by a collection of literary essays Visions and Revisions in 1915 and his first full length work of popular philosophy, A Complex Vision, in 1920.
In 1921 he met Phyllis Playter, the twenty-six year old daughter of industrialist and business man Franklin Playter. Eventually they established a permanent relationship, though he was unable to divorce his wife Margaret, who was a Catholic. Margaret Powys died in 1947, and his son Littleton Alfred in 1954.
It was not until 1929, with Wolf Solent, that Powys achieved any real critical, and financial success. A Glastonbury Romance, one of Powys’s most admired novels, which was published in 1932, also sold well, though he made little if any money from it because of a libel lawsuit. Another important work, Powys’s Autobiography, was published in 1934. Also in 1929 he and Phyllis had moved from Greenwich Village, in New York City to rural upstate New York. Then in June 1934 John Cowper Powys and Phyllis Playter left America and moved to England, living first in Dorchester, the setting for the final Wessex novel, Maiden Castle, before eventually moving to Corwen, Wales, in July 1935, with the help of the novelist James Hanley, who lived nearby. Here Powys immersed himself in Welsh literature, mythology and culture, including learning to read Welsh. The move inspired two major novels with Welsh settings, Owen Glendower  and Porius (1951). They later moved, in May 1955, to Blaenau Ffestiniog in North Wales. John Cowper Powys died in 1963 and Phyllis Playter in 1982.
JCP is a somewhat controversial "writer who evokes both massive contempt and near idolatry". Thus while Walter Allen in Tradition and Dream recognizes Powy’s genius, he is dissatisfied with what Powys has done with it, seeing Powys’s approach to the novel, as "so alien to the temper of the age as to be impossible for many people to take seriously". Annie Dillard, however, views things quite differently: "John Cowper Powys is a powerful genius, whose novels stir us deeply". What, however, is noteworthy is that consistently throughout his career he gained the admiration of major novelists, including Theodore Dreiser, Henry Miller, Iris Murdoch, Margaret Drabble, and James Purdy, as well as some academic critics, including George Painter, G. Wilson Knight, George Steiner, Harald Fawkner, and Jerome McGann. Film director John Boorman wrote in his autobiography that early in his career he contemplated making a movie based on A Glastonbury Romance.
Powys’s first published works were collections of poems published in 1896 and 1899, but these, and three subsequent volumes in 1915, 1916 and 1923, are of minor importance. However, the Welsh poet and critic Roland Mathias thought this side of Powys worthy of critical study: The Hollowed-Out Elder Stalk: John Cowper Powys as Poet.It was not until 1915 that he published his first novel, Wood and Stone, which was dedicated to Thomas Hardy.
While he was famous lecturer and published a variety of both fiction and non-fiction regularly from 1915, it was not until he was in his early fifties, with the publication of Wolf Solent in 1929, that he achieved critical and financial success as a novelist. This novel was reprinted several times in both the USA and Britain. In the same year The Meaning of Culture was published and it too was frequently reprinted. In Defence of Sensuality, published at the end of the following year, was yet another best seller.Before Wolf Solent there had been four earlier apprentice novels; Wood and Stone (1915), Rodmoor (1916), the posthumous After my Fashion (1980), which was written around 1919, and Ducdame (1925). Wolf Solent was the first of the so-called Wessex novels, which include A Glastonbury Romance (1932), Weymouth Sands (1934) and Maiden Castle.(1936). The latter is set in Dorchester, Thomas Hardy’s Casterbridge, and there are parallels with that earlier work. All the same despite his indebtedness to the Victorian novel and his enthusiasm for Hardy and Walter Scott, as well as lesser figures such as Ainsworth, Powys was clearly a modernist, with affinities also with Dostoievsky, Nietzsche, Pater, Proust, Jung, Freud, Lawrence, Joyce, Dorothy Richardson, and the T. S. Eliot. of The Waste Land.
It is clear from Powys’s diaries that his new found success was greatly helped by the stability that his relationship with Phyllis Playter gave him and her frequent advice on his work in progress.
A Glastonbury Romance sold particularly well in its British edition, though this was of little avail as it was the subject of an expensive libel case. First published in 1933 A Philosophy of Solitude was another best seller for Powys in the USA.While Welsh mythology was already important in A Glastonbury Romance and Maiden Castle it became even more important after he and Phyllis Playter moved to Corwen, Wales in 1935. First in the minor novel Morwyn (1937). There then followed two major historical novels set in Wales, Owen Glendower  and Porius (1951). The first deals with the rebellion of the Welsh Prince Owen Glendower (A.D.1400-16), while Porius takes place in the time of the mythic King Arthur (A.D. 499). However, Arthur is a minor character compared with the Welsh Prince Porius, and the King’s magician Myrddin (Merlin). In both works, but especially Porius, Powys makes use of the mythology found in the Welsh classic The Mabinogion. Just as the landscape of Dorset and Somerset, and the characters deep personal relationships with it, had been of great importance in the great Wessex novels, so the landscape of Wales, especially that of the Corwen region, became now of equal significance.
The landscape and the intimate relationship that characters have with the elements, including the sky, wind, plants, animals, insects, etc., is of great significance in all Powys’s works. This is linked to another major influence on Powys, Romanticism, especially William Wordsworth, and writers influenced by Wordsworth, such as Walter Pater. Powys was also an admirer of Goethe and Rousseau. Words such as mysticism and pantheist are sometimes used in discussing Powys’s attitude to nature, but what he is concerned with is an ecstatic response to the natural world, epiphanies such as Wordsworth describes in his "Ode: Intimations of Immortality" – with an important difference, because Powys believes that the ecstasy of the young child can be retained by any adult who actively cultivates the power of the imagination. Some have compared this to zen and such contemplative practices and for Powys, and the protagonists of his novels who usually resemble him, the cultivation of a psycho-sensuous philosophy is as important as the Christian religion was for an earlier generation.Porius is, in some eyes, the crowning achievement of Powys’s maturity but others are repelled by its obscurity. It was originally severely cut for publication but in recent years two attempts have been made to recreate Powys’s original intent.
The novels that followed Porius are more minor in scale and an element of fantasy is a special characteristic of them. In Atlantis even the inanimate world is allowed to speak. Some of the very last works would presumably not have been published if submitted by an unknown writer, though even they have their champions.
One of Powys’s most important work, his Autobiography, was published in 1934. While he sets out to be totally frank about himself, and especially his sexual peculiarities and perversions, he largely excludes any substantial discussion of the women in his life. The reason for this is now much clearer because we now know that it was written while he was still married to Margaret, though he was living in a common-law relationship with Phyllis Playter.
Periodically, over almost 50 years, starting with Confessions of Two Brothers in 1916, Powys wrote works that present his personal philosophy of life. These are not works of philosophy in the academic sense and in a bookstore the appropriate section might be self-help. Powys describes A Philosophy of Solitude (1933) as, a "short textbook of the various mental tricks by which the human soul can obtain ... comparative happiness beneath the normal burden of human fate" (7). It might seem that Powys’s various works of popular philosophy were mere potboilers, written to help their finances while he was working on his novels, but critics like Denis Lane, Harald Fawkner and Janina Nordius believe that they give insight into "the intellectual structures that form the metastructures of the great novels".
Taking advantage of his reputation as an itinerant lecture, Powys published in 1915 a collection of literary essays, Visions and Revisions. In the next forty years he published a couple of similar works, as well as three studies of writers, Dorothy Richardson (1931), Dostoivesky (1947), and Rabelais (1948), respectively. While not especially profound or original in their insights, they are full of the author’s infectious enthusiasm for literature. There is also a work on John Keats, part of which was published posthumously and Powys was working on a study of Aristophanes in his later years.
John Cowper Powys was a prolific writer of letters, many of which have been published, and kept a diary from 1929, some of which has also been published. Among his correspondents were the novelists Theodore Dreiser, James Purdy, James Hanley, Henry Miller and Dorothy Richardson, but he also replied to the many ordinary admirers who wrote to him.
One repeated theme in Powys' work is condemnation of animal cruelty, especially vivisection. As a result, some writers have claimed he anticipated the modern animal rights movement. This included not surprisingly opposition to fox-hunting. Powys was also a vegetarian, but probably more for dietary than ideological reasons.