The son of a Muscogee mother, Sehoy II, and a Scottish father, Lachlan McGillivray, he was literate and received an education in the British colonies.

"[2] McGillivray was born Hoboi-Hili-Miko (Good Child King) in the Coushatta village of Little Tallassee (also known as Little Tallase, Little Talisi and Little Tulsa) on the Coosa River, near present-day Montgomery, Alabama, on December 15, 1750.

[14] His predecessor, Chief Emistigo, died while leading a war party to relieve the British garrison at Savannah, which was besieged by the Continental Army under General "Mad" Anthony Wayne.

[19] McGillivray opposed the 1783 Treaty of Augusta,[20] under which two Lower Creek chiefs had ceded Muscogee lands from the Ogeechee to the Oconee rivers to Georgia.

[22] He sought to create mechanisms of centralized political authority (in himself), to end the traditional village autonomy by which individual chiefs had signed treaties and ceded land.

Armed by British traders operating out of Spanish West Florida, the Muscogee raided back-country European-American settlers to protect their hunting grounds.

In 1786 a council of the Upper and Lower Creek in Tuckabatchee declared war against Georgia; the Spanish officials opposed this, and after they told McGillivray they would reduce aid if he persisted, he entered into peace talks with the U.S.[21] A Loyalist like his father, McGillivray resented the developing United States Indian policy; however, he did not wish to leave Creek territory.

Georgia's Yazoo land scandal convinced President George Washington that the federal government needed to control Indian affairs rather than allowing the states to make treaties.

In 1790 he sent a special emissary to the southeast, who persuaded McGillivray and other chiefs to attend a conference with Henry Knox, the Secretary of War, in New York City, then the capital of the U.S.

The U.S. government promised to remove illegal white settlers from the area, and the Muscogee agreed to return fugitive black slaves who sought refuge with the tribe.

[25] The treaty temporarily pacified the Southern frontier, but the U.S. failed to honor its obligation and did not eject white settlers who were illegally on Creek lands.

In addition, he was a "secret partner" of the trading firm Panton, Leslie and Company, one of his principal sources of power, according to Thomas Jefferson, who met him in 1790.

His health began to fail; as Michael D. Green writes, "Never a robust man, he suffered throughout his adult life from the effects of syphilis and rheumatism.

"[28] He died on February 17, 1793, in Pensacola and was buried in William Panton's backyard and garden, wrote Edward Forrester, a mixed-blood trader among the Lower Creeks, in a letter to Nepomuceno de Quesada, the Spanish governor of East Florida at St. Augustine.