The Port Credit settlement grew slowly, at first. The town plot was laid out in 1834; however, it was not until the government gave the Port Credit Harbour Company $11,500 to rebuild the harbour facilities that the settlement really began to expand. With these improvements, Port Credit was able to export lumber and grain. Within 15 years, the town grew to a population of 250. The first permanent structure to have been built in the village was the Government Inn. Lieutenant Governor John Graves Simcoe had ordered construction of the Inn to serve as a way station for travellers.
In 1855, a branch of the Great Western Railway opened through Port Credit. Because the railway increased the exportation business, the village continued to expand.
Later in the 19th century, Port Credit became known for its stone hooking trade. This trade, started around 1815, covered the area from Port Whitby to Port Nelson, but approximately half of all the stone hooking schooners were owned by Port Credit. These ships set out on Lake Ontario to collect stone, mainly Dundas shale. Workers dragged large rakes along the bottom of the lake to gather the stone, and then lifted it into the ship. This stone was used to construct many buildings in Toronto, as well as in Port Credit and its surrounding communities.
Other industries such as the St. Lawrence Starch Works (1889-1989) and the Port Credit Brick Yard (1891-1927) provided employment for many local residents.
Port Credit was incorporated as a village in 1914. By 1961, it had a population of 6,500 and was incorporated as a town. It did not unite with its neighbouring settlements when they joined together to form the Town of Mississauga in 1968. Port Credit joined its neighbours to form the City of Mississauga in 1974.