Collins was born in August 1847 in Virginia, probably into slavery. Information about him is scarce, and the scattered documents that mention him often contain inconsistencies or suggest that those who recorded the information may not have known much about him. It is possible, but by no means certain, that he was a Norfolk native who married Rebecca Fuller in that city on July 11, 1866. A marriage license identifies the groom on that occasion as John H. Collins, a twenty-one-year-old student and son of Margaret Collins. What is certain is that in the summer of 1870 Johnson Collins, Rebecca Collins, and their sons, ages three and one, were living near his brother, a tanner, in Brunswick County. He and his wife later had two other children who died in infancy or childhood. Collins worked as a laborer, but so far as land and tax records show, he never owned any real estate. He may occasionally have used only his surname. The census enumerator in 1870 listed him as Collin Collins and his younger son, who was thereafter usually called Johnson Collins Jr., as Collin Collins Jr.
In November 1879 Collins narrowly won a three-way race for a seat representing Brunswick County in the House of Delegates. He defeated two white men, the Republican incumbent who favored paying off the antebellum state debt in full and a Readjuster who wanted to reduce the amount of the debt to be paid and to refinance the balance at a lower interest rate. Two voters cast ballots for Collin Johnson, suggesting continued confusion about his name or that he was not well known in some parts of the county.
Identified in one newspaper as a Republican and in another as a Readjuster, Collins served in the General Assembly that met from December 3, 1879, through March 9, 1880. He was appointed to a low-ranking seat on the Committee on Federal Relations and Resolutions and to the lowest-ranking seat on the relatively inconsequential Committee on Public Property. At the opening of the session Collins voted with the dominant coalition of Republicans and Readjusters to elect the Speaker, clerk, and other House officers and again two weeks later when the assembly elected the Readjuster leaderto the . Collins supported a proposed constitutional amendment to eliminate the as a prerequisite for voting and another measure that the Readjusters favored to reduce the tax on vendors of malt liquor, spirits, and wine. On March 1, 1880, he voted for a bill to reduce the principal of the public debt by about 40 percent and to refinance the remainder at 3 percent interest. Called the Riddleberger Bill, after its sponsor, state senator , it passed, but the governor vetoed the measure, and the Senate of Virginia sustained the veto.
In June 1880, when Collins gave information about his family to the census taker, who recorded his name correctly this time, he identified himself as a literate laborer and added, perhaps with pride, that he was a member of the state legislature, a fact the enumerator carefully recorded. Collins did not seek reelection in 1881 but received six votes anyway. Sometime during the next half-dozen years he and his family moved to Washington, D.C., where he worked as a watchman for about two decades. Collins died of heart disease in Washington on November 3, 1906, and was buried in the city’s Columbian Harmony Cemetery. In 1960 all of the graves were removed to National Harmony Memorial Park in Prince George’s County, Maryland.