Prichard was born at Llandovery in 1579; he was the eldest son of prosperous parents. He went to Brecon Grammar School, then in 1597 to Jesus College, Oxford. He was ordained in 1602, being appointed vicar of Llandingad, his native parish in which the town of Llandovery is situated. One of his parishioners was Sir George Devereux, who was uncle to Elizabeth’s favourite, the Earl of Essex. On the Earl’s execution, his son was in the care of Sir George and Prichard became his chaplain. Through his influential friend Pritchard became Rector of Llanedi, Carrmarthenshire in 1613, prebendary of the collegiate church of Brecon, and in 1626, the Chancellor of St David’s. Considering his evangelical sentiments and anti-papist views, it is surprising that he had so much favour; it says much for the merit of the man. Pluralism, the holding of more than one appointment, was rife in Wales at that time, but for once people were blessed as they had a good man teaching them. Wherever he preached the crowds were so large that he had to preach in the open air; even at the Cathedral of St David he preached in the courtyard. This offended the High Churchmen and they had him up before the spiritual court, but no action was taken.
Prichard was always a sound conformist but most of his converts, after his death, formed themselves into Nonconformist societies. For the first 28 years of his ministry the people did not have Bibles so he began to speak to the people through poems. These poems became very popular when they were published after his death; several of the most striking verses became national proverbs. Some of his poems criticised the disgraceful character of the clergy and the moral degradation of his countryman, just as Penry did. Since they were not published until after his death, he escaped punishment. He died in December 1644, but his grave is unknown.