Gardener Jean-Louis Cayrou has been found guilty of the premeditated murder of his British expat lover Patricia Wilson at her rural French home in 2012.
Cayrou, 54, was sentenced to 30 years in prison for killing Wilson, 58, following the collapse of their relationship, after the jury deliberated for almost five hours at the Cour d'Assises de l'Aveyron in Rodez, south France.
Gasps were heard from members of his family as he received his sentence, which he has 10 days to appeal against.
Wilson's mother, Jean Wilson, 84, said "justice has finally been done" following the verdict.
Cayrou is believed to have cut the electricity at Wilson's home near the village of Vabre-Tizac, in the Aveyron region of south-west France, after she returned from visiting her mother in England on August 17 2012.
He entered the property and killed Wilson, hitting her "very violently" at least twice and possibly with a weapon, general lawyer Manon Brignol said in her closing statement.
Cayrou, described as "dominating" and "unstable" by Brignol, left a trail of blood through the isolated French house, leading down the steps outside, where he is believed to have loaded Wilson's body into his car.
His prints and DNA were found at the crime scene and traces of Wilson's blood were discovered in his car.
Wilson's body has never been found and Cayrou's refusal to disclose where he hid it has been condemned by the prosecution.