Joshua Komisarjevsky's accomplice is already on Connecticut's death row.
Dr. William Petit, the only survivor of the attack, closed his eyes as the verdict was read.
Komisarjevsky and Steven Hayes were accused of tying up Petit's family during a home invasion, molesting the women, dousing the victims in gas and leaving them to die in a fire.
Petit, who had been beaten with a baseball bat, broke free from the post he was tied to in the basement and crawled and rolled his way to a neighbor's house.
Komisarjevsky, 31, was found guilty of all 17 charges he faced, including capital felony killing, kidnapping and sexual assault.
"I thought from the beginning that he was a lying sociopathic personality and probably at this moment he doesn't think he is guilty of anything," Petit told reporters outside the courthouse.
Prosecutors say the two paroled burglars spotted Petit's wife and youngest daughter at a grocery store on July 22, 2007, and followed them back to the house.
Hayes forced Petit's wife to withdraw money from a bank before he raped and strangled her in the family's Cheshire home. The girls, who had pillowcases placed over their heads, died after the house was doused with gas and set on fire.
During more than two weeks of testimony, prosecutors played an audiotaped confession in which Komisarjevsky spoke matter-of-factly and laughed occasionally. He admitted beating Petit and molesting his younger daughter and taking photos of her.
Connecticut's death penalty has only been implemented once in the past 51 years, when serial killer Michael Ross was executed in 2005.
The Associated Press contributed to this report.