McMinn fought during the American Revolutionary War in the Continental Army of the Americans. After the war he settled as a farmer in Hawkins County of the future state of Tennessee. In 1790 he was given by Governor William Blount his first public employment in a district administration. In 1794 he became a deputy in the Parliament of the then South-West Territory. In 1796 he was a member of the Constitutional Convention of Tennessee. He was then elected to the Senate of the new States. Later, he was Chairman ( Speaker) of this body for three legislative sessions. In 1815 he was elected to succeed Willie Blount for the fifth governor of Tennessee. Overall, he graduated to 1821 three two- year terms. During this time the capital of Tennessee Knoxville was moved to Murfreesboro (1819 ). However, the city already had to resign in 1826 to Nashville this function. The so-called Jackson Purchase Tennessee has been extended to 14 counties to the west. In addition, the Bank of Tennessee was founded during the term of office of McMinn. After his third and final term in 1821 he bought a farm near the village Calhoun. In 1823 he was appointed Indian agent among the Cherokee. He died in November 1824 in its Indian agency.
McMinn was married three times. In 1785 he married Hannah Cooper, who died in 1811. 1812 Rebecca Kincade was his second wife, but died in 1815. His third wife was Nancy Williams, whom he married in 1818 and from whom he was later divorced.