He was chosen as a delegate to five of the ten statehood conventions that secured Kentucky's separation from Virginia and helped write the state's first constitution.

He lobbied for public education, militia and prison reforms, business subsidies, and legislation favorable to the state's large debtor class.

Under the resulting constitution, the governor was popularly elected and was forbidden from succeeding himself in office, although Garrard was personally exempted from this provision and was re-elected in 1799.

During his second term, he applauded Thomas Jefferson's purchase of Louisiana from France as a means of dealing with the closure of the port at New Orleans to U.S. goods.

Late in his term, his Secretary of State, Harry Toulmin, persuaded him to adopt some doctrines of Unitarianism, and he was expelled from the Baptist church, ending his ministry.

He also clashed with the legislature over the appointment of a registrar for the state land office, leaving him embittered and unwilling to continue in politics after the conclusion of his term.

[13] While serving in the militia in 1779, Garrard was elected to represent Stafford County the Virginia House of Delegates,[12] and he assumed his seat for the 1779 legislative session.

[13] Acting on favorable reports from his former neighbor, John Edwards, Garrard and Samuel Grant headed west into the recently created Kentucky County.

[6][12] In 1789, the Virginia legislature established a permanent county seat named Hopewell, and Garrard was part of the committee chosen to survey the area for the city.

[32] Before the final convention in 1792, a committee composed of Garrard, Ambrose Dudley, and Augustine Eastin reported to the Elkhorn Baptist Association in favor of forbidding slavery in the constitution then being drafted for the new state.

Delegate David Rice, a Presbyterian minister, was the leading voice against the inclusion of slavery protections in the new constitution, while George Nicholas argued most strenuously in favor of them.

[12] His most notable action not related to slavery occurred on April 13, 1792, when he reported twenty-two resolutions from the committee of the whole that provided the framework for the new constitution.

[39] Todd, who had served as secretary of all ten Kentucky statehood conventions, had the most political experience, but his youth was considered a disadvantage by some.

[39][40] Garrard benefited from his political connections in Bourbon County, and many held him in high regard due to his work in the Baptist church.

[43] Although he did not believe Garrard had personally done anything wrong, Logan formally protested the outcome of the election to Kentucky Attorney General John Breckinridge.

[45] Garrard then appointed Harry Toulmin, who had resigned the presidency of Transylvania Seminary in April due to opposition from the institution's more conservative trustees.

[40] Although he did not retain outgoing Attorney General John Breckinridge, who had sided with Logan in the disputed gubernatorial election, Garrard still frequently consulted with him on complex legal questions.

[46] Shortly after Garrard took office, the state commissioners of public buildings reported to the legislature that it would be more financially sensible to construct a house for the governor and his large family than to rent living quarters for them for the duration of his term.

[48] Kentucky historian Thomas D. Clark also relates that Garrard's addition of carpeting to the mansion – a rare amenity at the time – drew many visitors and was described by one as "the envy and pride of the community".

[52] The legislators convened on November 28, and Garrard, drawing on his experience as a surveyor, addressed them regarding the urgency of adopting a new law and forestalling more lawsuits related to land claims, which were already numerous.

Garrard was supportive of the reforms – which included the abolition of the death penalty for all crimes except murder – and lobbied for the education of incarcerated individuals.

[52] On February 10, 1798, Garrard's son William, still serving in the state senate, introduced a bill to hold another vote on calling a constitutional convention.

[69] The closure of the port to U.S. goods represented a major impediment to Garrard's hopes of establishing a vibrant trade between Kentucky and the other states and territories along the Mississippi River.

[56] He urged President Thomas Jefferson to act and publicly declared that Kentucky had 26,000 militiamen ready to take New Orleans by force if necessary.

[70] Jefferson was unaware, however, that the secret Treaty of San Ildefonso had ceded control of Louisiana to the French dictator Napoleon Bonaparte in 1800, although a formal transfer had not yet been made.

[69] The Kentucky General Assembly quickly passed a measure guaranteeing 150 acres of land to anyone who volunteered for military service, and Garrard was soon able to inform Jefferson that his quota was met.

[72] The Senate then rejected Garrard's next nominee, John Coburn, and accused the next, Thomas Jones, of "high criminal offense" and barred him from any further appointive office.

[73] Accusations of bad faith were exchanged between the governor and the Senate, after which Garrard nominated John Adair, the popular Speaker of the House.

[73] His dispute with the General Assembly over the naming of a land registrar left Garrard embittered, and he retired from politics at the expiration of his second term.

[28] His son James oversaw the day-to-day operation of the farm and frequently won prizes for his innovations at local agricultural fairs.