Robert Barnes played a significant role in the early English Reformation. Like many who strived for religious reform during that period, he lived a life of great risk for the sake of his beliefs.

He received his education at Cambridge University and graduated with a doctoral degree in divinity. Not long after he was appointed to the prestigious position of Prior of the Cambridge convent. Most scholars agree that he was among a group of Cambridge students and alumni who regularly gathered at the White Horse Tavern for meetings to discuss the Bible and theology in general. This was a group that advocated reform. Barnes chose to publicly reveal his reformist zeal at the Christmas Midnight Mass, at St. Edward's Church. In his sermon, Barnes urged believers to turn to the simple truths found in the Gospel and accused the Church of many heresies.

His sermon is considered by some to be the first of the English Reformation. As a result of his efforts, Barnes was ordered to appear before the powerful Cardinal Wolsey, who at that time had the ear of King Henry VIII. Barnes was also questioned by four other bishops. He was given a choice: retract and deny his beliefs or be burnt at the stake for his beliefs. Barnes wisely chose to recant his statements and beliefs, and was imprisoned. He escaped from prison in 1528 and left immediately for Antwerp, Belgium. A little later on he found his way to Witternburg, Germany, where he met with Martin Luther. He also met a good friend of Thomas Cromwell, who was considered King Henry's right-hand man. Cromwell's friend, Stephen Vaughan, worked as an agent for Cromwell, and he sent a glowing recommendation of Barnes to England, stating, "Look well upon Mr. Barnes' book. It is such a piece of work I have not yet seen any like it. I think he shall seal it with his blood."

By 1531, Barnes decided to return to England. By that time, Reformation was a much more acceptable topic, especially since King Henry was considering a break from the Roman church. Through his new connection with Cromwell, Barnes was able to receive notice at court. He became an important intermediary between England and Germany, and traveled there in hopes of obtaining approval from Lutheran leaders for Henry to divorce his first wife, Catherine of Aragon. Much later, Barnes was part of the committee sent to negotiate a marriage between Henry and Anne of Cleves. Problems resulting from the latter (Henry was most displeased with Anne of Cleves) cast Cromwell, Barnes, and others in a bad light. Barnes' zealous rants favoring further reform were no longer welcome, and he was forced to apologize and recant once again.

Ever a political animal, Cromwell cut his ties with Barnes. Following Henry's divorce from Anne of Cleves, Barnes was sent to the tower and in 1540 was burned.