He was the eldest son of Henry in and Eleanor of Provence, born when his father had already reigned for over twenty years. Thanks to his father's long reign, Edward was able to ascend to the throne in the flower of his manhood. Thankfully he had also matured, for his youth, whilst spent as part of a loving family, was also tempestuous. In 1254, when only fifteen, he was married to Eleanor of Castile. Eleanor was herself barely thirteen and was known as the infanta of Castile. To English ears this sounded more like Elephant and Castle and gave rise to the name of many inns and taverns, and through them the district in south London. It was a political marriage in order to protect the southern borders of Gascony, England's last possession in France. The governorship of Gascony had been in the hands of Simon de Montfort whose autocratic rule had caused considerable unrest. Edward was invested as duke of Gascony at the time of his marriage, and acknowledged his fealty to the French king, the sainted Louis IX. However, Edward's command of Gascony does not seem to have been any less turbulent than De Montfort's. It appears Edward ruled with a strong hand and was not averse to severe retribution if any of his subjects challenged his authority.

At the same time (1254) Edward had been invested with lands in Wales and Ireland, and his first experience of warfare came in the uprisings in Wales when in 1256 the Welsh, under the leadership Of Llywelyn Ap Gruffydd, rebelled against the English imposition of a system of county administration. Peace was rapidly concluded because Henry III was facing his own internal problems in the rebellion of the barons. Edward initially sided with Simon de Montfort in producing the Provisions of Westminster in 1259, but later supported his father in the war that broke out in 1264. It was Edward who captured the younger Simon de Montfort at Northampton, but it was also Edward's youthful rashness that led to his capture alongside his father at the battle of Lewes later that year. Edward succeeded in escaping his custody a year later and in August 1265 routed and killed the elder De Montfort at the battle of Evesham. Henry's retribution on the disaffected barons was severe and those who were disinherited fought back from a stronghold at Ely in 1267. It was Edward who overpowered the barons, and it was his military skill and show of strength that helped bring a peace to England by 1269.

Edward was now thirty and, in 1270, set out on a long-awaited Crusade to the Holy Land. Although his escapades were not entirely glorious, there was much derring-do suitable for later retellings in adventure stories. Edward succeeded in relieving Acre from one of its many sieges by the troops of the sultan of Egypt, and won a victory at Haifa, but he was also wounded by a poisoned dagger wielded by an Assassin. Had he died English history would have been significantly different, and there would certainly have been a succession crisis with no adult heir. Edward recovered, however; this was later said to be thanks to his wife who sucked the poison from the wound. He was in Sicily on his way home when, in November 1272, he learned of his father's death. It is an indication of how confident Edward was in his English regents that he did not hurry home. Instead he travelled triumphantly through Italy as a Crusader hero and new king, and on through France to pay homage to the new French king, Philippe 111. He eventually returned to England on 2 August 1274, with his coronation held seventeen days later.

The coronation was a momentous occasion, but a small cloud over it would cast a long shadow. Llywelyn ap Gruffydd, the prince of Wales, failed to attend to pay homage. Edward commanded him to attend his court on two later occasions and even travelled to Chester in 1276 to make it easier. When Llywelyn rebuffed him for a third time, Edward acted with lightning effect. He declared Llywelyn a rebel and thus anyone supporting him would be a traitor. When Edward brought his forces into Powys opposition immediately crumbled, and Edward was able to penetrate into Gwynedd and force Llywelyn into submission. Under the Treaty of Aberconwy in November 1277, Llywelyn retained the now hollow title of prince of Wales, and held authority over only Gwynedd, west of the Conway, and was forced to share that with his brother. Llywelyn, though humiliated, endeavoured to remain respectful of Edward to the extent that in October 1278 Edward allowed the long promised marriage between Llywelyn, and his cousin, Eleanor, the daughter of Simon de Montfort. This arrangement had been made in 1265, when Eleanor was only thirteen. Unfortunately Eleanor died in childbirth four years later, just at the time that actions by Llywelyn's brother Dafydd caused a further rebellion in Wales and Llywelyn, possibly against his will, was forced back into the limelight. Edward, believing he had previously treated Llywelyn with surprising leniency, was furious. Although the Welsh offered more resistance than in 1278, Edward was able to call upon much greater resources than the Welsh. Victory was almost certain to be Edward's, but it was made more complete when Llywelyn was killed in a skirmish in December 1282. His renegade brother held out for a further four months but was arrested in April 1283 and executed for treason six months later. Edward was no longer prepared to tolerate the perpetual hostility from the Welsh. On 19 March 1284 the Statute of Wales was enacted, bringing Wales under the direct government of England. Wales now held the status of a colony of the Crown, and justice was administered by three sheriffs. Edward also set up a series of new lordships, some of which were granted to the dispossessed Welsh princes, but others to Edward's own barons. In June 1284 Edward celebrated his conquest of Wales by holding an Arthurian Round Table court at Nefyn. The festivities were so well attended that the floor of the court gave way under the strain. One of the legends attached to this period is that Edward promised he would grant them a prince who had been born on their own soil, and promptly presented to them his young son, Edward, who had been born in April 1284. Edward was not officially invested as prince of Wales until February 1301.

The Welsh exploits were but one chapter of Edward's early reign, though a significant one. Much of his energy was directed toward a survey of England and a reformation of feudal jurisdictions in the country’s legal system. Soon after his coronation he despatched commissioners throughout his kingdom to establish who held what authority over what land and whether there had been any abuse of power. Hitherto barons holding lands in fief from the king had often administered the king's laws within their territories, but many abused this privilege. In many cases barons claimed this had been their right since time immemorial, because they were unable to produce charters granting them such authority. Edward recognized that authority granted in the time of Henry II (his great grandfather) was early enough to qualify as time immemorial, particularly given the unstable years of Stephen and Matilda’s civil war, but anything more recent had to be supported by written evidence. With this established Edward was able to put the collection of taxes and other revenues on a much firmer footing, and he was also enabled to reconstruct his authority and that of his barons in a more clearly codified set of laws. Edward needed clarity over his revenues to enable him to finance his extensive military campaigns. This time, however, he determined to appease the barons by gaining their assent to his tax collection. The combination of tax and legislative reforms in consultation with his peers was what brought about the evolution of government by Parliament. A Great Council had met since the time of John, but it did not have the representative element of a formal Parliament. With his Statute of Westminster in 1275 Edward inaugurated reforms which led, over the next twenty years, to the establishment of a formal parliament. During this process Edward was quick to punish those who had abused their authority. In this way Edward endeared himself to the commoners of England, who saw him as their saviour. The one group to which Edward did not endear himself was the Jews. In 1278 he had passed an enactment which allowed all Jews in England to be arrested on the grounds of coinclipping. Some 280 of them were hanged. The Jews had been one of the main alternative sources of income in England, but the Crusades had brought a reaction against them. While barons and royalty were keen to borrow their money, they had no desire to repay it and even introduced laws to stop the Jews claiming land in forfeit for non-payment. By Edward's reign the Jews were themselves becoming impoverished and the rising tide of nationalism in England increased the public antipathy to them. In 1290 Edward expelled all of the Jews from England, over sixteen thousand of them, on the grounds of usury. Thereafter the merchants became royal creditors, especially those from Venice and Lombardy in Italy.

Edward had long set his eyes on the conquest of Scotland. An opportunity arose in 1290 when Margaret, the infant queen of Scotland (and Edward's great-niece) died. Edward had previously agreed with Alexander III that the young queen would marry his son and heir Edward (later Edward II) which he hoped would lead to the union of England and Scotland. Margaret's death scuppered that plan, but Edward was now consulted by the Scottish magnates to adjudicate over the succession. In 1292, Edward eventually nominated John Balliol, a fair decision, but also a weaker choice than the other primary candidate, Robert The Bruce, and one whom Edward could more easily dominate. Nevertheless over the next few years the Scots grew tired of John as a spineless pawn of Edward and incited him into rebellion in 1295. This came as a result of a difficult set of circumstances which now plagued Edward. In 1294 the French king Philippe IV had taken possession of Gascony. Edward had summoned a parliament to approve the collection of taxes for his campaign against France, but there was considerable resentment, especially north of the border where the Scots were expected to pay a tax for a war against the French, whom they regarded as their ally. At that same time, in October 1294, the Welsh took advantage of the French diversion to rebel, with Madog ap Llywelyn declaring himself prince of Wales. Edward was now facing rebellion on three fronts. It is evidence of his mastery of the situation that he was able to resolve all three in quick succession. From December 1294 to March 1295 he led his armies into Wales, defeated all opposition and slaughtered the main ringleaders. Back in England Edward summoned the first Model Parliament, which consisted of representatives of all three estates: the church, the barons and the shires and burghs. With the agreement of this parliament he was able to raise further revenues and enact plans for his campaigns in Scotland and France. Edward took his forces north, sacked and plundered Berwick in March 1296 and defeated John Balliol at Dunbar on 27 April. John surrendered two months later and was imprisoned in the Tower of London. Edward proudly seized the symbol of Scottish kingship, the Stone of Scone, which he brought south to Westminster, where it would remain for seven hundred years. Edward now believed he had conquered Scotland and left three magnates in authority. He needed to turn his attention to France. Parliament was less keen to raise further revenues for a French campaign, but regardless Edward sailed for France in 1297 and, through the intervention of the pope, was able to make a truce with France whereby he also regained control of Gascony. Thus in the space of two years Edward had held his possessions on two fronts and extended them on a third. The Scottish advance, however, was more chequered than Edward had anticipated. His three administrators proved unequal to their task and the tyrannical oppression of one of them, William Ormsby, had stirred the Scots back into revolt under William Wallace. Edward now led a further army north, defeating Wallace at Falkirk on 22 July 1298.

Over the next few years Edward sought the total subjugation of the Scots. His many campaigns, which culminated in the capture and execution of Wallace in August 1305, seemed to deliver Scotland firmly into his hands. And yet, even as he was in the process of confirming a constitution for Scotland another rebellion erupted, this time under Robert Bruce. Despite his age and increasing infirmity, Edward prepared for a further campaign. He marched north and was in sight of Scotland when he died of dysentery at Burgh-on-Sands near Carlisle in July 1307. Edward believed he had conquered the Scots and thus must have died disappointed at not seeing his vision complete. Nevertheless, unlike any ruler before him (and most since), he had the skill, strength and authority to undertake the task and failed ultimately only by his underestimation of the strength of the Scottish spirit.

Edward's first wife, Eleanor, had died in 1290 of a fever near Grantham while she was travelling north to meet Edward in Scotland. Edward had been devoted to her and was sorely grieved at her death. As her body was conveyed back to London, he established crosses at the sites where her body rested each night. There were originally twelve of these, of which the best known were at Waltham and Charing Cross. Eleanor had borne Edward sixteen children, the most from one legitimate union to any king of England. However few of these survived infancy and only four of them outlived Edward. Three of these were daughters, but the fourth was Eleanor's youngest son Edward. King Edward had remarried in 1299, this time to Margaret the sister of Philippe IV of France. It was another political marriage yet, although Edward was sixty and Margaret scarcely twenty, the match seemed to work, and Margaret bore Edward three more children.

Although Edward failed to conquer Scotland, his conquest of Wales has left its mark on Britain ever since, though possibly his most lasting legacy was the firm establishment of Parliament.