Welsh First Minister Mark Drakeford will also address the conference on Saturday, while Shadow Chancellor John McDonnell will speak on Sunday.
Saturday will see policy debates on education, local government and equalities – with the latter now including a statement from the party executive about anti-Semitism after local party groups had been denied an emergency motion on the topic.
Mr Leonard’s speech will outline what he calls the party’s “progressive agenda for workers rights”.
He will say: “Let me start with the Michelin workers in this city, who I met at the factory just a few weeks ago.
“They told me that Michelin did not close the factory, the market closed the factory. Our message to them is that you have the 100% support of the Scottish Labour Party.
“A few weeks ago I met workers in Dundee who were employed by McGills, who told me they had been let down: badly let down by the company’s bank which foreclosed an overdraft and badly let down by the Scottish government, which could have stepped in to rescue these jobs, but who sat back.
“This is a city where decent industrious people have been let down by the failed economic system, where too much power rests in too few hands – often in faraway boardrooms.”
On Friday, Mr Corbyn issued a plea for party unity after rows about Brexit and anti-Semitism, telling delegates that “the only thing that can hold us back is if we were to turn our fire on each other rather than on the Tory government”.