The jury had the options of the death penalty or life in prison without parole for Sowell, convicted July 22 of killing 11 women whose remains were found in and around his Cleveland home.
The jury had begun deliberating Tuesday afternoon and returned its verdict Wednesday, The Cleveland Plain Dealer reported.
As Sowell was led out of the courtroom by sheriff's deputies, family members of some of Sowell's victims broke into applause.
Cuyahoga County Judge Dick Ambrose will formally sentence Sowell on Friday.
Ambrose cannot impose the death penalty without the recommendation from the seven women and five men of the jury, but does have the power to reduce a death penalty recommendation to life in prison, The Plain Dealer reported.
Sowell addressed the jury earlier this week.
"The only thing I want to say is that I'm sorry," he told them. "I know that may not seem like much. And I'm sorry from the bottom of my heart."