Henry Bett, 28, of Thornham, near Hunstanton, killed Rebecca Brown, 43, when his tractor hit her car in December 2013.
Bett, son of Stephen Bett, was jailed in 2015 but the conviction was quashed.
At a retrial a jury at Cambridge Crown Court found him guilty of causing her death by dangerous driving.
Bett, of Ling Farm Cottages, was released on bail and will be sentenced later this month.
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Mrs Brown, of Castle Acre, Norfolk, died when the Fiat people carrier she was driving was crushed in the collision with Mr Bett's Fendt tractor on the West Acre Road at about 15:10 GMT on 4 December 2013.
Bett was initially found guilty of causing her death by dangerous driving in August 2015 and jailed for three and a half years.
He was freed by the Appeal Court in London in September.
The court ordered that no details of the arguments in Bett's appeal could be published for legal reasons but appeal judges said he must be retried.
At the retrial in Cambridge Bett denied causing Mrs Brown's death by dangerous driving, but admitted causing death by careless driving.
However, he was found guilty by a majority verdict of 10 to two.
The son of a former Norfolk police and crime commissioner has been found guilty at a retrial of causing the death of a woman by dangerous driving.