Conrad was born in Wittemberg, Germany to John Conrad Weiser and Anna Maria Uberle (who died when Conrad was 12). In 1710, Conrad and his father came to America, along with 150 other German families. They purchased land from the Mohawk Indians near Schoharie, New York.
Conrad's father soon became friends with Chief Quagnant of the Mohawk who invited Conrad Jr. (age 17) to spend the winter with his tribe to learn the language and ways of his nation. After spending a year among the Mohawk he returned home and became a valuable asset as an interpreter between the Germans and the Mohawks.
In 1755, during the Indian outbreaks along the frontier, Weiser was appointed Colonel of a regiment of volunteers from Berks County, PA. A number of forts were constructed under his direction along the frontiers of Lancaster and Berks counties. During the "French and Indian War", he commanded the Second Battalion of the Pennsylvania Regiment. The Pennsylvania Archives states that Weiser's Indian name as "Tarachawagon" or "Tasachawagon", which means "he who holds the reins".
Conrad was also a business man and acquired quite a bit of property in the Pennsylvania area. At the time of his death, Conrad's estate included some 900 acres of land in Heidelberg Township, Berks County; Blue Mountain lands; and a lot in the town of Reading. In 1751 he erected a large stone home, which was also the first store in Reading. After the original building burnt down in 1907, a new facsimile was built and is now a museum to honor this unassuming national hero. At the age of 64, he died at his home on July 11, 1760.