He served in both the House of Delegates and the State Senate before being appointed to the Virginia Supreme Court of Appeals (which later became the Supreme Court of Virginia). He was educated by tutors and in private grammar schools in Fredericksburg. During the American Revolution he was active in the militia and served on General Greene"s staff with the rank of lieutenant.
He was admitted to the bar in 1788 and practiced in Monongahela and Harrison counties.
Later he was made Commonwealth’s Attorney in the district court and practiced in Essex County, Virginia, where he was elected to the House of Delegates in 1794. Two years later he moved to Fredericksburg and was elected to the State Senate in 1800.
After the Revolution, Brooke remained active in the Virginia militia and was promoted to the rank of major in 1796, lieutenant colonel in 1800 and brigadier general in 1802. In 1811 Brooke was appointed a judge of the Supreme Court of Appeals and was president of that court for eight years, from 1823 to 1831.
He was elected again in 1831 and held the office until his death on March 3, 1851.
He was an original member of the Virginia Society of the Cincinnati.