With his death Owain acquired a mythical status along with Cadwaladr, Cynan and Arthur as the hero awaiting the call to return and liberate his people. Thomas Pennant, in his Tours in Wales (1778, 1781 and 1783), searched out and published many of the legends and places associated with his memory. Previously, George Owen, in his A Dialogue of the present Government of Wales (1594) had written against the Cruell lawes against Welshmen made by Henrie the ffourth in his attempts to quell the revolt. But it was not until the late 19th century that Owain's reputation was revived. The "Young Wales" movement recreated him as the father of Welsh nationalism. The discovery of Owain's Great Seal and his letters to the French in the Bibliothèque Nationale helped revise historical images of him as a purely local leader. In the First World War, the Welsh Prime Minister, David Lloyd George, unveiled a statue to him in Cardiff City Hall and a postcard showing Owain at the Battle of Mynydd Hyddgen was sold to raise money for wounded Welsh Soldiers. Folk memory in Wales had always held him in high regard and almost every parish has some landmark or story about Owain. However, there is no road sign indicating the scene of one of his greatest battles at Bryn Glas in 1415.
In 1808, the Royal Navy launched a 36-gun fifth-rate frigate, which it named the HMS Owen Glendower. She served in the Baltic during the Gunboat War where she participated in the seizure of Anholt Island, and then in the Channel. Between 1822 and 1824, she served in the West Africa Squadron (or 'Preventative Squadron') chasing down slave ships, capturing at least two.
In 1875, the Rev. Francis Kilvert wrote in his diary that he saw the grave of "Owen Glendower" in the churchyard at Monnington "[h]ard by the church porch and on the western side of it ... It is a flat stone of whitish grey shaped like a rude obelisk figure, sunk deep into the ground in the middle of an oblong patch of earth from which the turf has been pared away, and, alas, smashed into several fragments."
He is now remembered as a national hero and numerous small groups have adopted his symbolism to advocate independence or nationalism for Wales. For Example, during the 1980s, a group calling themselves "Meibion Glyndŵr" claimed responsibility for the burning of English holiday homes in Wales.
Glyndŵr was the hero of James Hill's UK TV movie Owain, Prince of Wales, broadcast in 1983 in the early days of Channel 4/S4C.
Glendower Residence, at the University of Cape Town in South Africa was named after Owain Glyndŵr. The residence was opened in 1993 having previously been the Glendower Hotel. It now houses 139 male and female undergraduate students.
The creation of the National Assembly for Wales brought him back into the spotlight and in 2000 celebrations were held all over Wales to commemorate the 600th anniversary of Glyndŵr's revolt, including an historic reenactment at the Millennium National Eisteddfod of Wales, Llanelli 2000. Stamps were issued with his likeness in 1974 and 2008 and streets, parks, and public squares were named after him throughout Wales. Owain’s personal standard — the quartered arms of Powys and Deheubarth rampant — began to be seen all over Wales, especially at rugby union matches against the English. A campaign exists to make 16 September, the date Owain raised his standard, a public holiday in Wales. An annual award for achievement in the arts and literature, the Glyndŵr Award, is named after him. In 2007, popular Welsh Musicians the Manic Street Preachers wrote a song entitled "1404" based on Owain Glyndŵr. The song can be found on the CD single for 'Autumnsong'. A statue of Owain Glyndŵr on horseback was installed in 2007 in The Square in Corwen, Denbighshire, to commemorate his life and his lasting influence on Wales. Also located on the Square in Corwen is the Owain Glyndwr Hotel. The waymarked long distance footpath Glyndŵr's Way runs through Mid Wales near to his homelands.
Owain Glyndŵr came 2nd in the 100 Welsh Heroes poll of 2003/4.
In 2006, Adrien Jones, the President of the Owain Glyndŵr Society, said, "Four years ago we visited a direct descendant of Glyndŵr, a John Skidmore, at Kentchurch Court, near Abergavenny. He took us to Mornington Straddle, in Herefordshire, where one of Glyndŵr's daughters, Alice, lived. Mr Skidmore told us that he (Glyndŵr) spent his last days there and eventually died there.... It was a family secret for 600 years and even Mr. Skidmore's mother, who died shortly before we visited, refused to reveal the secret. There's even a mound where he is believed to be buried at Mornington Straddle."
For a study of the various ways Glyndŵr has been portrayed in Welsh-language literature of the modern period, see E. Wyn James, Glyndŵr a Gobaith y Genedl: Agweddau ar y Portread o Owain Glyndŵr yn Llenyddiaeth y Cyfnod Modern (English: Glyndŵr and the Hope of the Nation: Aspects of the Portrayal of Owain Glyndŵr in the Literature of the Modern Period) (Aberystwyth: Cymdeithas Llyfrau Ceredigion, 2007).
In 2008, Glyndŵr University was established in Wrexham, Wales. Originally established as the Wrexham School of Science and Art in 1887, it was until the name change known as the North East Wales Institute or "NEWI". Glyndŵr was born and lived much of his life around Wrexham and the Welsh Marches.
In his book The Mystery of Jack of Kent and the Fate of Owain Glyndŵr, Alex Gibbon argues that the folk hero Jack of Kent, also known as Siôn Cent – the family chaplain of the Scudamore family – was in fact Owain Glyndŵr himself. Gibbon points out a number of similarities between Siôn Cent and Glyndŵr (including physical appearance, age, education, and character) and claims that Owain spent his last years living with his daughter Alys, passing himself off as an aging Franciscan friar and family tutor. There are many folk tales of Glyndŵr donning disguises to gain advantage over opponents during the rebellion.
With his death Owain acquired a mythical status along with Cadwaladr, Cynan and Arthur as the hero awaiting the call to return and liberate his people. In the late 19th century the Cymru Fydd movement recreated him as the father of Welsh nationalism.