Daniel Jones, 29, set a house in Stanley, Wakefield, alight in October 2016 in a bid to destroy CCTV evidence of a nearby break-in.
Andrew Broadhead, 42, and his daughter Kiera, eight, died in the fire.
At Leeds Crown Court, Jones, of Knottingley, was cleared by a jury of murder but convicted of manslaughter.
Judge Mr Justice Morris gave special permission for Kiera's 13-year-old sister Mia to read a statement, in which she described her sibling as the "world's brightest star".
The teenager wiped away tears as she said her father was "the world's greatest superhero".
The court heard Mr and Mrs Broadhead and their two daughters were asleep in their home in the early hours of 19 October when Jones poured petrol through their front door letterbox and set it alight.
Mrs Broadhead and Mia managed to escape, but Mr Broadhead and Kiera were overcome by the rapidly spreading smoke and fire and were later pronounced dead at the scene in Ash Crescent.
The jury heard how Jones was worried that CCTV footage from the home would reveal a raid he carried out three days earlier.
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