The news was confirmed to Fox News in a statement from Presley's rep, via her manager.
"She is completely heartbroken, inconsolable and beyond devastated but trying to stay strong for her 11-year-old twins and her oldest daughter Riley," said the statement. "She adored that boy. He was the love of her life."
TMZ reported that Keough died Sunday of a self-inflicted gunshot wound, citing law enforcement sources.
Lisa Marie Presley (left) and Benjamin Keough. (Getty)
Compared to some of his family members, Keough has lived a relatively spotlight-free life. He has one acting credit on IMDb and TMZ reported that he once had a $5 million record deal in 2009.
He was also known for his striking resemblance to Elvis, which, according to the outlet, Presley once addressed.
"Ben does look so much like Elvis. He was at the Opry and was the quiet storm behind the stage," she said. "Everybody turned around and looked when he was over there. Everybody was grabbing him for a photo because it is just uncanny."
Reportedly, Presley's song "Storm and Grace" is about Keough, whose middle name is Storm.