Al Sharpton will eulogize Nichols, and another prominent civil rights leader, attorney Ben Crump, will deliver a "call to action" during a funeral at the Mississippi Boulevard Christian Church in Nichols' adopted hometown of Memphis.
Among those planning to join the mourners was U.S. Vice President Kamala Harris, whom Crump said the Nichols family invited.
Harris spoke with Nichols' mother, RowVaughn Wells, in a private telephone call on Tuesday, he said.
Two other officers implicated in the events leading to Nichols' death have been relieved of duty - effectively suspended - and are under investigation.
"What happened to Tyre Nichols here is a disgrace to this country," Sharpton told reporters, flanked by Nichols' mother and his stepfather, Rodney Wells.