“I have known Frank for over 50 years, and have shared many memories since we met when we came to Johannesburg,” he said in a statement.
“Frank was a dedicated, loyal and hard-working member of my branch who always put the interest of the people before his own.”
Frank Sexwale, who was a World War Two veteran and the father of former Cabinet minister Tokyo Sexwale, has died at the age of 97. It is not known when he died.
He will be buried in Heroes Acre at Avalon Cemetery in Soweto on Saturday.
Mlangeni said he regretted that he would not be there as he is in Cape Town and not feeling well.
“I will never forget many good and sad moments Frank and I shared before and after the attainment of our hard-earned democracy,” he said.