He became president of a machine shop making ball bearings in 1899. In 1916 and 1918, his company merged with United Motors Corporation and with another company to form General Motors Corporation, which started making cars. He became Vice-President, then President (1923), and finally Chairman of the Board (1937). In 1934, he established the philanthropic nonprofit Alfred P. Sloan Foundation.
Under Alfred P. Sloan's leadership, public transport systems of trams in the US were successively replaced by buses. Many of the trams themselves were literally burnt in order to prevent any reversal in public transport policies. Frequencies of bus services were decreased on less profitable routes, helping to encourage people to buy their own automobiles and travel independently (but with a higher fuel/km/person cost than for trolleys or even buses).
In these ways and others, Alfred P. Sloan continued to increase GM's profitability.
Sloan retired as chairman in 1956 and died in 1966.