Edward was the eldest son of Sir Alexander Unton (occasionally spelt Umpton), of Wadley House at Littleworth in Faringdon, Berkshire, by his second wife, Cecily, the daughter of Edward Bulstrode of Hedgerley in Buckinghamshire. His father died when he was only thirteen and he succeeded, in name at least, to the family estates. He was brought up by his mother and educated as a lawyer at the Inner Temple in London.

By February 1553, Cecily Unton had remarried to the Surveyor-General of the Court of Wards, Robert Keilway. He had previously been legal advisor to the Protector of the Realm, the now disgraced (and executed) Edward Seymour, Duke of Somerset. Not long afterwards, during the reign of Queen Mary, Keilway arranged, firstly, for his step-son to be elected MP for Malmesbury in Wiltshire at the age of only twenty; and, then, for him to enter into a matrimonial alliance with a member of the depressed house of Seymour. His new wife was the sixteen-year-old Anne, the eldest daughter of the Lord Protector, and widow of John Dudley, Earl of Warwick, the eldest son of his great rival, the Duke of Northumberland. Both the Dudleys had opposed Mary's accession to the Throne. So it is perhaps not surprising that the marriage was solemnized in a scene far different to that which had witnessed the former splendid but calamitous alliance of the lady. It took place on 29th April 1555, not in the busy market town of Faringdon, but in the small and sequestered old church in the adjoining parish of Hatford, a short distance from Edward's mansion of Wadley. It has been suggested that this was in an attempt to keep the union quiet. If so, it was certainly unsuccessful. For Edward was arrested by the Privy Council in the November and spent over a month in the Fleet Prison, being released just before Christmas. The marriage seems to have eventually been approved, however, as Anne was granted a life interest in many of the lands forfeited by her former husband. Furthermore, even if the marriage did not add to Unton's personal happiness - which it may well have done for the two had seven children together - upon the restoration of Protestant ascendancy, it certainly added materially to his family influence, the lady being sister-in-law to Queen Elizabeth's favourite, Robert Dudley, the great Earl of Leicester.

Sir Edward Unton was one of the Knights of the Bath, created at the Coronation of Queen Elizabeth, in January 1559. He lived mostly in London and was good friends with Sir Francis Walsingham and even named one of his sons after him. However, he seems to have been something of a hot-head as shown by an incident which occurred outside Temple Bar in November 1562. With a group of friends and their servants, he was out on the Strand one day making rather too much noise and, no doubt, blocking the highway to some extend, when they met another group of young lads coming the other way. Friendly banter quickly turned to threats and a brawl ensued. Swords were drawn and a member of the opposing party, Richard Grenville (the later sea-captain and explorer), ran threw a certain Robert Bannister and killed him. Sir Edward seems to have escaped unharmed in either physique or reputation.

 In 1563, Sir Edward sat for Oxfordshire in Parliament but, the following year, he quit the country temporarily in order to make a tour of Italy. In the British Library is preserved a very small pocket volume, containing "The Journey of Sir Edward Unton and his company into Italy, wherein is contained the names of the towns where he baited and lay, and the distance of miles between them," which "was written by Richard Smith, gentleman, sometime servant to Sir Edward Unton of Wadley in the county of Berks, knight." The party boarded ship at Dover on 12th March 1564. The volume is unfinished, but continues on as far as the journey from Strasbourg to Mentz during the return trip, on the 27th October. Among several books once belonging to the Untons, which are still preserved in private libraries, are two which form memorials of their Italian travels: a copy of "Historic di Nicolo Machiavelli, cittadino et Secretario Fiorentino" and one of "Le Antichita della Citta di Roma," both printed in Venice (1537 & 1562).

By 1566, Lady Unton was enjoying poor mental health and Sir Edward seems to have thrown himself into Courtly life and offices in London. The following year, he served the office of Sheriff of Berkshire, being the first Sheriff for that county alone, on its separation in that respect from Oxfordshire. He sought re-election to Parliament in 1571 but, as the Oxfordshire seats had been sown up by the Norreys and Knollys families, he decided to try his luck in Berkshire. However, the long arm of Sir Henry (later Lord) Norreys (Sir Edward's 4th cousin) stretched even there and his protégé, Sir Richard Warde of Hurst, was elected instead. Sir Edward did not forget. He bore a grudge and, at the Abingdon Quarter Sessions that followed in the Autumn, his servants attacked those of Sir Henry's son, John. At the Star Chamber case that followed, the reason for the attack became clear and Sir Edward even claimed that Sir Henry had fixed the election with ballet papers from tenants who had no right to vote. The following year, Sir Edward Unton was finally elected MP for Berkshire and, eight years later, the two men may have been reconciled when they worked together to secretly search out Jesuits in Oxfordshire.

Sir Edward was always much favoured by Queen Elizabeth and, during her summer progresses in September 1572, August 1574 and August 1575, he received her at Langley, his Oxfordshire home at Leafield, near Burford, possibly while his mad wife was hidden away at Wadley. During the middle visit, Sir Edward presented her with a handsome jewel, which we find thus officially described among the "Jewels given to her Majesty in progress-time” (1574):
"First, one jewel of gold garnished with diamonds and rubies and five pearls pendant, one bigger than the rest. Given to her Majesty by Sir Edward Umpton, Knight. The same delivered to Mr. Secretary Walsingham, by her Majesty's commandment"
Sir Edward made similar offerings to the Queen at New Year in 1572:
"one fair flower of gold enamelled, and garnished with a chrysolite and an emerald, and fully furnished with rubies, diamonds and pearls, and three pearls pendant; two ounces qa and a farthing gold weight. Given by Sir Edward Umpton, Knight."
And in 1581: "a pair of bracelets of gold, containing sixteen pieces, in every of them a small ruby garnished with small pearl. Given by Sir Edward Unton."

After having to have his leg amputated, Sir Edward languished in agony for three months before finally dying on the 16th September 1582 and, three days later, his will was proved in the Prerogative Court of Canterbury. He was buried in Faringdon Church under a fine mural monument sporting many heraldic allusions to the Seymour's great heritage. However, the funeral did not take place until another three months after his death, possibly in the hope that his eldest son, Edward, would be able to return home from abroad to attend.