A native of Georgia, Garrard Glenn received his B.A. in 1899 from the University of Georgia and went to Columbia Law School from which he received an LL.B. in 1903. While a student there he served on the editorial board of the Columbia Law Review with John M. Woolsey, founder of the journal. Upon graduating he worked five years for Davies, Stone and Auerbach in New York. He then helped establish the firm of Shattuck and Glenn. In 1913 Glenn began lecturing at Columbia and continued there as a part-time associate professor until 1921. He had devised a course called Creditors' Rights which so impressed the Columbia faculty that they hired him to teach it. In early 1927 Glenn turned down the offer of a teaching position at the University of Virginia Law School, but in December he decided to accept. He was the James Monroe Professor of Law from 1929 until his death in 1949. Glenn, a well-loved and respected professor, taught Trusts, Equity, Corporations, Evidence, Creditors' Rights, Security and Insurance.

Garrard Glenn's prolific writing career began while he was a student and extended through the years of ill-health preceding his death. In 1910 he published Secret Liens and in 1915, Creditors' Rights, a major work in an area of the law which he helped bring into focus. World War I prompted him to write The Army and the Law, and in 1931 he published Fraudulent Conveyances. Naturally after he began teaching Glenn had more time for scholarship, and in the thirties and forties his most respected works were written. He also served as editorial adviser for Jurisprudence in Virginia and West Virginia and the Restatement of the Law of Security. Glenn produced more than 40 major articles for law reviews across the country and covered topics from creditors' rights to Sir Thomas More, whom he felt should be the patron saint of his profession. While at the University, he served on the faculty committee of the Virginia Quarterly Review and was a faculty advisor to the Virginia Law Review. Leslie Hepburn Buckler described Glenn’s teaching style: “Every student he ever taught will agree he was a great teacher. But he violated, or rather ignored, all the rules declared essential by the authorities on ‘legal teaching, method and objectives,’ whether according to the fashion that is in the ascendant, or the one which is in decline.” Armistead M. Dobie was to claim in his later years that his greatest contribution to the Law School was his ability to persuade Glenn to come to Virginia.