After becoming an adult, he was for some time a distiller, but afterward engaged in the dry-goods trade, and founded the house of Gardner Brewer & Co., which represented some of the largest mills in New England, and had branches in New York and Philadelphia.
In this business, by accurate method combined with great sagacity, he accumulated a fortune, which, at his death, was estimated at several millions of dollars.
He was also a strong protectionist, and took great interest in the industrial development of the country.
He used his large wealth liberally for the public good, and shortly before his death gave to the City of Boston a beautiful fountain, which stands on an angle of the common.
His residence, on the site of the house of John Hancock, is one of the finest private dwellings in the city.