The garda Cold Case Unit is to conduct a "full review" of the murder of Sophie Toscan du Plantier in west Cork in 1996.
Ms Toscan du Plantier was found dead on a laneway leading to her holiday home in Schull on 23 December 1996.
Following a review by the Assistant Commissioner for Organised and Serious Crime, the Garda Serious Crime Review Team will now conduct a full review of the case.
This team reviews unresolved historical and current major crime incidents with the aim of assisting in identifying new investigative opportunities in a case.
"On the finalisation of this review, the Serious Crime Review Team will provide recommendations to the local investigation team," gardaí said.
Gardaí said the investigation into her murder has remained active up until the review and is ongoing.
Former journalist Ian Bailey was convicted in his absence of the murder of Ms Toscan du Plantier by a French court three years ago.
Mr Bailey has always maintained his innocence in relation to the killing.
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His solicitor Frank Buttimer said his client "is very happy that An Garda Síochána have decided to carry out a cold case review".
"He has advocated for it over a period of time," Mr Buttimer said.
"To the extent that he can, or that he may be required, he will assist the enquiry."
Mr Buttimer said that he was sure that today's announcement by An Garda Síochána to carry out a full review of the murder of Ms Toscan du Plantier, will come as a relief to her family.
Over the past 25 years, there has been a number of enquiries including the McNally Review, the McAndrew Review, as well as the Fennelly Commission of Enquiry.
The case has been reviewed, Mr Buttimer said, but "it is hoped that this one will achieve a positive outcome for everyone, but most particularly for the family of Madame Toscan du Plantier".
Gardaí continue to appeal to anyone with information to contact the investigation team at Bantry Garda Station or the garda confidential line 1800 666 111.