Joseph Cordiano (born October 30, 1957) is a politician in Ontario, Canada. He is a current member of the Legislative Assembly of Ontario, and is a cabinet minister in the government of Liberal Premier Dalton McGuinty.

Cordiano was born in Toronto, Ontario, the son of Italian immigrants. He was educated at the University of Toronto and the University of Toledo in Ohio, graduating from the latter with a Master's Degree in Business Administration. Before entering political life, he was the owner and General Manager of Cash Rolls of Canada.

Cordiano was first elected to the Ontario legislature in the provincial election of 1985, defeating incumbent New Democrat Odoardo Di Santo by 221 votes in the Toronto riding of Downsview. He was re-elected by a greater margin in the redistributed riding of Lawrence in the provincial election of 1987. Cordiano was not appointed to cabinet during the government of Liberal Premier David Peterson (1985-1990), but served as Parliamentary Assistant to a number of ministers.

The Liberals were upset by the NDP in the provincial election of 1990 and Cordiano faced a difficult challenge from NDP candidate Shalom Schachter , winning by 11786 votes to 10179. He subsequently emerged as a prominent voice for the provincial Liberal Party within Toronto. The provincial election of 1995 saw Cordiano win by a comfortable margin — the provincial swing was to the Progressive Conservative Party, but the PCs did not have enough support in Lawrence to seriously compete for the riding.

When Lyn McLeod resigned as Liberal leader in 1996, Cordiano announced his candidacy to succeed her. At first, many saw him as the leading challenger to frontrunner Gerard Kennedy, who was regarded as representing the left-wing of the party. Cordiano, in turn, was seen by many as representing the party's establishment, while holding some right-wing leanings.

The leadership convention was held in November 1996. Cordiano finished second to Kennedy on the first ballot, but was unable to build upon his position in later counts. Dalton McGuinty tied him for second place on the third ballot, and overtook him on the fourth. Cordiano supported McGuinty on the fifth ballot, and was thereby largely responsible for McGuinty's victory over Kennedy for the party's leadership. Cordiano was subsequently named as Deputy Leader of the Opposition, and held this position until 1997.

Cordiano and Kennedy were again rivals in the provincial election of 1999, this time for the Liberal nomination in the redistributed riding of York South—Weston. Kennedy was convinced by the party leadership to run elsewhere, and Cordiano won an easy victory in the election which followed. The Progressive Conservatives won the general election, however, and Cordiano remained on the opposition benches. In 2000, he was appointed opposition critic for financial institutions.

The Liberals won the provincial election of 2003, and Cordiano won another easy victory in York South—Weston. On October 23, 2003, Cordiano was named Minister for Economic Development and Trade .

Cordiano is the cousin of federal MP and Cabinet Minister Tony Ianno.