Mairead Philpott, 31, and her husband Michael Philpott, 56, were on trial for killing Duwayne Philpott, 13, Jade Philpott, 10, John Philpott, 9, Jack Philpott, 8, Jesse Philpott, 6 and Jayden Philpott, 5, in a fire they started at their home in May 2012, the British newspaper The Mirror reported.
Paul Mosley, 46, a friend of the Philpotts, was also convicted of manslaughter in the trial.
Michael Philpott -- an unemployed father of at least 15 children -- was known in British media as "Shameless Mick." He publicly flaunted the fact that he shared a home with his wife and a mistress, Lisa Willis.
Prosecutors said the Philpotts were trying to frame Willis, who lived in the home for 10 years before leaving in February 2012, a few months before the fire.
During the trial, Mairead Philpott denied starting, or seeing anyone start, the fire, but admitted she agreed to her husband's relationship with Willis to avoid losing what she had.
She referred to her husband as a "guardian angel," whom she met as a 19-year-old single mother at "rock bottom."
Witnesses at the trial said Michael Philpott had a history of exploiting young women who had serious personal problems and few resources.
After the verdicts were announced Tuesday, the family of Mairead Philpott issued a statement saying "justice has been served and we are happy with the verdict."