Brown was still performing with the Blue Notes until January, when he became ill while singing at a show in Chester. He died Sunday, according to the Mitchum-Wilson Funeral Home.
Harold Melvin & the Blue Notes are known for songs including "I Miss You," "If You Don't Know Me by Now," "The Love I Lost," "Bad Luck" and "Wake up Everybody."
Despite frequent changes in personnel - including Teddy Pendergrass becoming the group's lead singer in the 1970s - Brown remained the second tenor.
He began singing and dancing as a child in Philadelphia.
"Lawrence's dreams as a performer truly became reality," his family said in an obituary. "Although he will be sorely missed, this talented, funny, life-loving man will live on in the hearts of all those who knew and loved him - and the magic that inspired him."
Brown, who lived in North Philadelphia, is survived by a wife and son.