Burchard oversaw the rebuilding of the walls of Worms, the creation of many monasteries and churches, and took part in the destruction of the fortifications of Duke Otto of Carinthia. Duke Otto was believed to be housing criminals, and was an enemy of Burchard's. According to Burchard's biographer "many limbs were hacked off and many murders occurred on both sides" of the conflict. Burchard adopted a child from the enemy household, who would grow up to become Emperor Conrad II. After gaining the aid of King Henry II of Bavaria and engaging in negotiations, Duke Otto's castle was dismantled and rebuilt to become a monastery in honour of St. Paul. In 1016 Burchard rebuilt the town's Cathedral of St. Peter. Burchard also spent time educating students in the cathedral's school.
Burchard is best known as the author of a twenty-book collection of canon law. Begun in 1008, the materials took him four years to compile. Burchard wrote it while living in a small structure on top of a hill in the forest outside Worms, after his defeat of Duke Otto and while raising his adopted child. The collection, which he called the "Collectarium canonum" or "Decretum", became the primary source for canon law. It came to be referred to as the Brocardus (Latin for 'Burchard'), from which the legal term 'brocard' originates.
Along with numerous documents from a variety of sources, including the Old Testament and Augustine of Hippo, Burchard included the Canon Episcopi in this collection, under the belief that it dated from a bishop's "Council of Anquira" in 314, but no other evidence of this council exists. Because of this inclusion, Burchard has been described as something of a rationalist. As the source of canon law, Burchard's Decretum was supplanted around 1150 by the Decretum Gratiani, a much larger collection that further attempted to reconcile contradictory canon law.
Burchard spent the years 1023 to 1025 promulgating Leges et Statuta familiae S. Petri Wormatiensis, a collection of religious laws he endorsed as fair and hoped to see adopted with official approval.