Armistead was the second of three sons and one of at least four children of William Armistead and Anne Armistead, of Kirk Deighton, Yorkshire, England. He may have been born in Virginia, his parents having settled in Elizabeth City County in the mid-1630s, which is the most likely approximate time of his birth. When he reached adulthood he moved to Gloucester County, where he lived and farmed for the rest of his life. His father had prospered so rapidly after immigrating to Virginia that both of his surviving sons began their adult lives as substantial planters. He may have sent John Armistead to Gloucester County in the 1650s to manage the properties he acquired after that section of the colony was first opened to English settlement.
Sometime in the 1660s Armistead became associated with Robert Beverley (1635–1687), an association that led to several profitable joint business ventures. The relationship grew even closer when Armistead married Beverley’s sister-in-law Judith Hone. Armistead had two sons and two daughters, and he acquired even more influential family connections later, when one of his daughters married Ralph Wormeley (d. 1701) and the other married Robert “King” Carter.
Destruction of most of the records of Gloucester County has obscured the details of Armistead’s participation in politics. He probably became a vestryman of Kingston Parish within a few years of moving to the county, and by 1670 he was a member of the county court as well as a colonel in the county militia. He became sheriff in 1676 and again in 1680. In 1682 he arrested several local women who were destroying tobacco plants. This put him in opposition to Robert Beverley, the putative instigator of the plant-cutting riots, by which the perpetrators hoped to reduce the supply of tobacco and thereby raise its price. Armistead differed from Beverley on political issues, too. Beverley grew increasingly outspoken in his opposition to English policies designed to control Virginia after Bacon’s Rebellion, while Armistead inclined favorably toward the new order.
Armistead served in the House of Burgesses twice. Elected in 1680, he sat at the first meeting of the General Assembly of 1680–1682. His part in suppressing the plant cutters may explain his absence at the second session, and he did not return to the House until 1685. By the mid-1680s he was on friendly terms with Governor Francis Howard, baron Howard of Effingham, who resided at times with Armistead’s son-in-law Ralph Wormeley. The association with Effingham proved beneficial, and in 1688 Effingham appointed Armistead to a vacancy on the governor’s Council. He was sworn in on October 18, 1688, but his tenure lasted only two and a half years. In April 1691, following the Glorious Revolution, Armistead refused “thro Scruple of Conscience” to swear allegiance to the new monarchs, William and Mary. He consequently lost his seat on the Council. Seven years later the Crown ordered him restored to his place, but Armistead did not take the oaths after the commission was presented to the Council on December 9, 1698.
John Armistead may have been dead by that date, but he could also have been alive and in political retirement in Gloucester County while continuing his refusal to forswear his oath to James II. The date and place of his death are not recorded.