Born September 1, 1791, son of John Molson (1763–1836) and Sarah Insley Vaughan, at Montreal, Quebec.
Thomas Molson was educated in private schools and apprenticed to the brewery trade.
On becoming a partner in John Molson & Sons in 1816, he took over the management of the family's brewery operations.
Under the firm-name of Thomas & William Molson it became one of the leading distilleries in North America.
Thomas Molson was a benefactor of McGill University and the Montreal General Hospital.