Griffin was born in Yorktown, and was the son of Maria Griffin, an enslaved woman who also had four daughters. He and his sisters were all the children of a prosperous white man, Robert Anderson, whose white family in Williamsburg refused to live with him. Early in the 1850s Anderson moved to Yorktown, where he wrote his will in 1857 and left his estranged wife a legacy, acknowledged Griffin and his sisters as his children, left them and their mother most of his property, and directed that they all be freed and that the children all be cared for and. Anderson died in January 1859, but his widow and heirs at law prevented the will’s provisions from taking effect before the (1861–1865).
As was common with enslaved people, public records contain almost no information about Griffin’s youth or when he learned to read and write. Nor do surviving records indicate precisely when he and his family became legally free. Sometime during the Civil War, Griffin and his mother and younger sisters in effect freed themselves. They moved to Philadelphia, where they lived with his elder sister and her husband.
On March 28, 1865, in Frankford, Pennsylvania, Griffin enlisted as a private in Company K, 24th Regiment United States Colored Troops. The surviving military service record described him as five feet, four inches tall with black or hazel eyes, and light-colored hair. The infantry regiment briefly guarded Confederate prisoners at Point Lookout, in Maryland, and then in the middle of July it was ordered to Virginia. Stationed first in Richmond, the regiment was soon transferred to Burkeville, in Nottoway County, where it distributed food and other supplies to freedpeople and helped preserve order. Griffin and the regiment mustered out of service in Richmond on October 1, 1865. The regiment’s motto on its battle flag was “Let Soldiers in War be Citizens in Peace,” which Griffin put into practice with his wartime service and his political career afterward.
Griffin returned to Philadelphia, but whether immediately after his discharge or later in the decade is unclear. While living there he married Caroline M. Johnson on August 21, 1871. They had three sons, one of whom died young. In April 1869 the family had hired a Richmond lawyer to claim the property Robert Anderson’s will bequeathed them. Griffin personally presented the will for probate at the courthouse in Williamsburg on October 12, 1871. In August 1872, when he was preparing to move back to Yorktown, the other members of the family deputized him to act for them in cooperation with the Richmond lawyer. The legal cases involving Anderson’s estate dragged on for years, and it is unclear how much of his father’s property they received. Griffin later purchased a few parcels of the several hundred acres of land in Yorktown and in the county that had belonged to his father. By 1876 Griffin was part owner of at least one lot in Yorktown. In 1877 he and a partner borrowed $600 to purchase a portable steam engine and sawmill, which they paid off in three annual installments. Griffin may have attached the engine to a gristmill and earned his livelihood for a time as a miller.
Soon after returning to Yorktown, he began taking an active part in African American political community in the county since shortly after the Civil War. Griffin provided transportation to the Republican candidate for Congress in 1874 and later testified at a congressional hearing into charges of bribery during the campaign. Griffin was not implicated. His Republican Party work earned him appointment as postmaster of Yorktown effective May 19, 1880. The following March, Griffin attended the that voted to affiliate with the new biracial that promised to refinance the pre–Civil War to reduce the rate of interest and the principal in order to be able to increase appropriations for the .politics, sometimes in partnership with his neighbors, the brothers and , who had been leaders of the
Griffin was still serving as postmaster on August 29, 1883, when the convention of the Readjuster-Republican Party coalition nominated him for a two-year term in the House of Delegates for the district that included the counties of York, Warwick, James City, and Elizabeth City and the city of Williamsburg. On November 6, in a three-man race against a and a white Republican who did not affiliate with the Readjusters, Griffin won with 2,412 votes to his competitors’ combined 2,262. In that election, the coalition of Readjusters and Republicans lost its majorities in both houses of the General Assembly to the newly reorganized .
Griffin submitted his resignation as postmaster on November 15 in order not to be in violation of a state law that prohibited federal employees from serving in the General Assembly, which began its session early in December; but he continued to act as postmaster through the remainder of the year because the Post Office Department did not replace him until March 1884. In the meantime, he took his seat as a member of the House of Delegates in December 1883 and was appointed to low-ranking seats on the relatively inconsequential Committees of Asylums and Prisons, on Executive Expenditures, and on House Expenses. On February 11, 1884, a member proposed to remove Griffin from his seat in the assembly because he continued to be postmaster of Yorktown. The Committee of Privileges and Elections recommended on March 3 that he be unseated, but after he stopped serving as postmaster the House of Delegates took no final vote on the proposal, and he remained a member of the house.
Griffin introduced six bills and one petition of local interest to people in the counties he represented. The only bill to pass was to charter the Band of Brethren Lodge, Number One Thousand Nine Hundred and Fifty, Grand United Order of Odd Fellows, a fraternal mutual service organization in Yorktown intended to provide relief and burial benefits for members. Griffin was one of the nine original members of its board of directors.
Democratic Party leaders in the General Assembly called it back into special session in August 1884. At that session Griffin introduced one unsuccessful local bill, and the assembly also took action to reduce African American voting and influence in politics. In November, near the end of the special session, it passed over the governor’s veto a law usually known as the Anderson-McCormick Act, which allowed the assembly (controlled by the Democrats) to appoint all officers of election and give them. Griffin had voted against a similar bill that was passed and vetoed by the governor during the regular session and he again voted against the bill when the delegates passed it over the governor’s second veto. Griffin either did not seek or did not receive the nomination to run for a second term in 1885.
Griffin ran for sheriff of York County in 1887 with Robert Norton’s aid but did not win. Griffin and his wife jointly or separately bought and sold several properties in the town and county during the next two decades. In 1900 the census enumerator identified all the members of his family as white rather than as of mixed race, which earlier and later enumerators did. The enumerator in 1900 listed Griffin as an oyster planter, indicating that he may have leased a reef from the state or from someone who had created an artificial reef to sow with oyster spat for later harvest. Ten years later the census listed him as a farmer.
Griffin’s wife died on September 24, 1918, after which he lived in the household of one of his daughters-in-law and may have later lived in Washington, D.C. Robert Gilbert Griffin died on February 9, 1927, and was buried in Eden Cemetery, in Collingdale, Pennsylvania.