On September 30, 1750, Thomas Bloss was granted an island in Halifax Harbour which later bore his name. Bloss Island was one of many names which referred to the island up until the latter part of the 19th century when it became widely known as Lawlor Island. In 1750, Governor Cornwallis wrote of Bloss:

Captain Bloss, a half-pay captain of a man- of-war is come here. He has brought with him 16 negroes - has built a very good house at his own expense, and is a sensible, worthy man. He is going home to pass some accounts that is necessary, being abroad many years.

Bloss went to England and was never seen again in Halifax. A man named Scott next obtained ownership of the island.

In 1758, the island bore the name Webb's Island. In 1792, it was referred to as Carroll's Island. In 1821, James Lawlor, into whose hands the island had passed, offered a reward for the conviction of persons who had stolen his sheep from the island. In this notice the island is referred to as McNamara's Island.

Haliburton, in 1829, refers to the island as Duggan's Island. He records that nine people lived there with six acres of land under cultivation. Shortly afterwards the island was referred to as Warren's Island.

In 1866, after an estimated 200 passengers and crew died of cholera on McNabs Island, the Provincial Government constructed a building for quarantine purposes near Green Hill, at the southern end of McNabs Island. Shortly afterward, however, the Imperial government acquired the southern half of McNabs Island from Lyttleton for military purposes, thus necessitating the purchase of a new site for the quarantine station.

In 1866, the Province acquired Lawlor Island for use a quarantine station. A central figure in providing these new facilities was Sir Charles Tupper who served as both city health officer and Premier of Nova Scotia at this time. He later became Prime Minister of Canada.

The quarantine building on McNabs island was dismantled in 1866 and re-erected on Lawlor Island. The threat of another cholera epidemic in 1871 prompted the construction of three quarantine hospitals on Lawlor Island capable of accommodating at least 500 people. In 1893, a disinfection building was added to the quarantine station. A small cemetery located at the extreme northern tip of the island was used as the final resting spot for those who died while at the quarantine station.

One of the most interesting episodes in the island's history occurred in 1899 when 2,000 Doukhobor immigrants were quarantined there. Persecuted in their native Russia, the Doukhobors were enroute to new homes in Western Canada with support from Leo Tolstoy and under the leadership of his son Count Sergius Tolstoy when their ship arrived at Halifax on January 28 with a possible outbreak of smallpox.

The Doukhobors were immediately removed to Lawlor Island where they were initially housed in building designed for only 1,400 people. Within days the hard working Doukhobors had constructed additional accommodations for themselves, along with a kitchen and enlarged bath house. After several weeks of fumigation, disinfection and vaccination, no cases of smallpox were reported. Shortly before departure, Count Tolstoy was interviewed by The Halifax Herald. Of his stay on Lawlor Island Tolstoy noted that it "was not at all to be compared with the rigors of Siberian banishment but still the three weeks spent there had been dull exceedingly."

The quarantine station on Lawlor Island was used occasionally in this century, but a better understanding of preventative health care and improved communications between ports greatly reduced the spread of infectious diseases. By 1938, the quarantine station was no longer needed on Lawlor Island. The island was subsequently purchased by the Canadian government for use as a medical facility during the Second World War. Today only the foundations and a few gravestones of the once busy quarantine station remain.

In 1864, during the American Civil War, McNabs and Lawlor islands played a small but important role in an incident involving several ships from the Confederate and Union navies. In the summer of 1864 the confederate raider Tallahassee sailed from Wilmington, South Carolina, and over the next several months attacked many ships destined for northern ports. On August 17 the Tallahassee entered Halifax Harbour to stock up on coal for the return trip to the Confederate port of Wilmington, Delaware. Under British neutrality laws, the Tallahassee had forty-eight hours to replenish her supplies and repair any damage before leaving harbour. With two Union ships thought to be guarding the main harbour channel, it seemed inevitable that the Tallahassee would be captured or destroyed soon after leaving the sanctuary of Halifax Harbour.

Neither the captain of the Tallahassee, John T. Wood, or his crew, though, were willing to admit defeat so easily. In the dead of night the Tallahassee prepared to escape from the harbour by passing through the shallow and dangerous Eastern Passage. Hidden from the awaiting Union vessels by McNabs and Lawlor Islands, the Tallahassee managed to slip out of Halifax Harbour unnoticed. In fact, the Tallahassee need not have worried about slipping out unnoticed as logs show the nearest Union ship was eight hours behind the Tallahassee arriving in Halifax.

Perhaps the most famous blockade runner of the war, the Tallahassee destroyed 35 ships during the war. Her captain, a grandson of Zachary Taylor, 12th president of the United States, settled in Halifax after the war and became a member of the city's business establishment. Interestingly, Captain Wood's son, Charles, was one of the first Canadians killed in South Africa during the Boer War. The community of Chaswood, Halifax County, is named in his honour.