The 26-year-old completed his move to Nice on Friday, September 18, and will remain with the Ligue 1 side until the end of the 2026/27 season. The deal does not include an option to buy.
Nice turned to Seidu after suffering defensive injuries to Antoine Mendy and Moïse Bombito, allowing the club to make use of the 'joker' rule despite the closure of the French transfer window on September 1.
The rule allows French clubs, under certain conditions, to recruit a player outside the normal transfer window. Nice identified Seidu as their priority defensive target because of his versatility and experience in Ligue 1.
The move brings an end to a difficult period for Seidu at Rennes. The Ghana international had been close to leaving the club during the summer transfer window, with Marseille, Strasbourg and Hull City among the clubs linked with a move for the defender.
Several proposals were rejected as Rennes and the player struggled to find an agreement on his next destination, with Seidu spending a period training away from the first team.
He eventually returned to full training with the Rennes squad and was included in Franck Haise's travelling squad for their Europa League meeting with Sturm Graz on September 16.
Seidu remained an unused substitute as Rennes played out a goalless draw in Austria.
His inclusion in the squad came just days before his eventual departure for Nice, where he will now look to revive his season and secure regular first-team football.
Seidu brings considerable Ligue 1 experience to Nice, having made 106 appearances in the competition for Clermont Foot and Rennes. He can operate as a right-back, right wing-back or centre-back.
Nice sporting director Roger Ricort highlighted that versatility following the move, while the club also pointed to Seidu's experience at two World Cups with Ghana.
Seidu has won 25 caps for the Black Stars and featured at the 2022 and 2026 FIFA World Cups but missed out on the recent squad for the 2027 Africa Cup of Nations qualifiers.
He will now continue his club career at Nice, with the opportunity to play a regular role during the remainder of the season.
