He was born 5 January 1209 at Winchester Castle, the second son of John, King of England and Isabella of Angoulême. He was made High Sheriff of Berkshire at the age of only eight, was styled Count of Poitou from 1225 and in the same year, at the age of sixteen, his brother King Henry III gave him Cornwall as a birthday present, making him High Sheriff of Cornwall. Richard's revenues from Cornwall helped make him one of the wealthiest men in Europe. Though he campaigned on King Henry's behalf in Poitou and Brittany, and served as regent three times, relations were often strained between the brothers in the early years of Henry's reign. Richard rebelled against him three times, and had to be bought off with lavish gifts.
In 1225 Richard traded with Gervase de Tintagel, swapping the land of Merthen (originally part of the manor of Winnianton) for Tintagel Castle. It has been suggested that a castle was built on the site by Richard in 1233 to establish a connection with the Arthurian legends that were associated by Geoffrey of Monmouth with the area. The castle was built in a more old-fashioned style for the time to make it appear more ancient. Richard hoped that, in this way, he could gain the Cornish people's trust, since they were suspicious of outsiders. The castle itself held no real strategic value.
The dating to the period of Richard has superseded Ralegh Radford's interpretation which attributed the earliest elements of the castle to Earl Reginald de Dunstanville and later elements to Earl Richard. Sidney Toy, however, has suggested an earlier period of construction for the castle.
In March 1231 he married Isabel Marshal, the wealthy widow of the Earl of Gloucester, much to the displeasure of his brother King Henry, who feared the Marshal family because they were rich, influential, and often opposed to him. Richard became stepfather to Isabel's six children from her first husband. In that same year he acquired his main residence, Wallingford Castle in Berkshire (now Oxfordshire), and spent much money on developing it. He had other favoured properties at Marlow and Cippenham in Buckinghamshire. Isabel and Richard had four children, of whom only their son, Henry of Almain, survived to adulthood. Richard opposed Simon de Montfort, and rose in rebellion in 1238 to protest against the marriage of his sister, Eleanor, to Simon. Once again he was placated with rich gifts. When Isabel was on her deathbed in 1240, she asked to be buried next to her first husband at Tewkesbury, but Richard had her interred at Beaulieu Abbey instead. As a pious gesture, however, he sent her heart to Tewkesbury.
Later that year Richard departed for the Holy Land, leading the second host of crusaders to arrive during the Barons' Crusade. He fought no battles but managed to negotiate for the release of prisoners (most notably Amaury VI of Montfort) and the burials of crusaders killed at a battle in Gaza in November 1239. He also refortified Ascalon, which had been demolished by Saladin. On his return from the Holy Land, Richard visited his sister Isabella, the empress of Frederick II.