Balfour, 31, was accused of killing the three in a jealous rage, believing that his estranged wife, Julia Hudson was seeing another man.
Jennifer Hudson, who sat between her fiance and Julia Hudson, silently cried as the verdict was read.
After three days of deliberations, the jury read the guilty plea as Balfour appeared to sit expressionless. He faces a mandatory sentence of life in prison.
Defense attorneys claimed the killings could have been related to Hudson’s brother’s alleged drug dealing. Hudson was the first witness called to the stand and she attended every day of testimony.