Ian Bailey has been ordered by a French judge to pay €115,000 in compensation to the family of Sophie Toscan du Plantier.
The 39-year-old film producer was found dead near Schull in West Cork on December 23rd, 1996.
Last month, a French court convicted Ian Bailey of her murder and sentenced him to 25 years in prison.
62-year-old Mr Bailey did not attend the trial.
He has repeatedly denied that he had any involvement in the murder, or that he ever made any admissions in relation to Ms Toscan du Plantier's death.
The conviction was welcomed by Ms Toscan du Plantier's family, with her only son Pierre-Louis Baudey-Vignaud calling it a "victory for justice".
Mr Bailey's solicitor Frank Buttimer, however, claimed the decision was a "grotesque miscarriage of justice".
Journalist Sarah Collins, who followed the trial in Paris, outlined the details of the new civil judgement.
She explained: "It does hold Ian Bailey completely responsible for the personal injury suffered by Ms du Plantier's family - entirely responsible is the words [the judge] used in her judgement.
"In one part of the judgement, it describes Mr Bailey as 'on the run and wanted', and said there was 'actual and certain' personal injury to the family - resulting directly from the acts for which Mr Bailey was convicted."
Mr Bailey is living in Ireland.
In 2012, the Supreme Court here rejected France’s first attempt to have him extradited on the ground there was no actual intention to try him.
In June 2017, the courts rejected a second extradition application from the French authorities.