Sarkozy, who had earlier been found guilty of illegal attempts to secure favours from a judge, will "evidently" respect the terms of the conviction after the Court of Cassation's verdict, his lawyer Patrice Spinosi told AFP.
But he will take the case to the European Court of Human Rights within weeks, Spinozi added.
This move at the Strasbourg-based ECHR will, however, not hold up Wednesday's verdict from being carried out. The sanction now comes into force, Sarkozy having exhausted all the legal avenues in the case in France.
Spinosi said it was a "sad day" when "a former president is required to take action before European judges to have condemned a state over whose destiny he once presided".
In 2021, a lower court found that Sarkozy and his former lawyer, Thierry Herzog, had formed a "corruption pact" with judge Gilbert Azibert to obtain and share information about a legal investigation.
The court sentenced him to a three-year jail term, two of which were suspended and one that was to take the form of home detention with an electronic tag allowing his movements to be monitored.
That verdict had already been upheld once, by an appeals court, last year.
Other cases pending
Sarkozy, 69, has always claimed his innocence, with his lawyer saying he would "not give up this fight".
The right-winger, who was president for one term between 2007 and 2012, failing to win re-election. He has been embroiled in legal troubles ever since leaving office.
The latest case, dubbed "Bismuth", comes on top of separate cases about campaign financing overspending, and the alleged financing by Libya of Sarkozy's 2007 election campaign.
Despite his legal problems, Sarkozy continues to enjoy considerable influence and popularity on the right of French politics and has the ear of President Emmanuel Macron, with whom he is known to meet on occasion.
Sources have told AFP that Sarkozy held talks at the Elysee earlier this month in a bid to persuade Macron not to appoint veteran centrist Francois Bayrou as prime minister. The former president is widely known to despise him.
After a long hesitation, Macron however went ahead and named Bayrou.
