“It’s a transfer record for Nice,” Nice director general Julien Fournier told AFP.
The 23-year-old left-back joined Nice in July 2016 from Portuguese club Vitoria Guimaraes in a deal estimated at two million euros.
His sale surpasses Nice’s previous record for French midfielder Nampalys Mendy to Leicester City in 2016 estimated at 17 million euros with French forward Loïc Rémy joining Marseille in 2010 for 15 million euros.
“We don’t have the commercial resources of big clubs, our development depends on the value and sale of players,” said Fournier.
“Even if on a sporting level we lose a very good player this transfer permits us to recruit like we have done this summer.”
Dalbert played 33 matches in Ligue 1 last season as Nice finished a surprise third behind Monaco and Paris Saint-Germain.
Meanwhile, Serie A club Fiorentina announced the signing of midfielders Valentin Eysseric and Marco Benassi from Nice and Torino respectively.
Eysseric, 25, signed a deal until 2021 worth four million euros.
Benassi, 22, a former Italy under-21 international, joined on a five-year contract estimated at 10 million euros, subject to a medical on Thursday.
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