Black served 42 months in jail at the Coleman prison in Florida on fraud and obstruction of justice charges before being released last month. Black originally faced more than a dozen charges laid by U.S. authorities, but he was convicted of just four by a jury.
He delivered a speech at a $70-a-plate luncheon hosted by the Empire Club in Toronto's downtown Sheraton hotel, his first major public appearance since being released.
Although he gave up his Canadian citizenship in 2001 to accept a seat in Britain's House of Lords, Black returned to his Toronto home last month after he was granted a one-year temporary resident permit.
The former media baron said America's waning influence in the world could present some opportunities to seize more global influence for Canada.
"The United States is a great nation but it is an extremely corrupt and inadequate criminal system," Black told the CBC's Peter Mansbridge in an exclusive interview last month.
Black's speech began a little after 1 p.m. ET.