Theodorick Bland practiced medicine in Virginia after medical study in Edinburgh, while also managing plantation property worked by enslaved people. The revolutionary crisis drew him into organizing resistance and obtaining arms. In 1776 he accepted a cavalry commission and rose to colonel of the First Continental Light Dragoons, often called Bland's Horse. His responsibilities included reconnaissance and reporting enemy movements directly to Washington, notably during the Brandywine campaign.

Ill health limited his field service, and he later supervised British and German prisoners of the Convention Army in Virginia. Elected to the Continental Congress, he represented Virginia from 1780 to 1783 during the transition from wartime mobilization to the Confederation government. He subsequently served in the Virginia House of Delegates and held militia responsibilities in Prince George County. His public work joined medicine, military administration and politics.

At Virginia's ratifying convention in 1788 Bland opposed the federal Constitution, sharing concerns about the strength of the proposed national government. After ratification he accepted the new system and won election to the first U.S. House of Representatives as an opponent of the administration's policies. He took his seat in 1789 and died in New York in June 1790 while Congress was meeting there. His papers preserve evidence of cavalry service, prisoner administration and Anti-Federalist politics.