Galtier's appointment comes after PSG president Nasser al-Khelaifi put an end to speculation that the club had been in talks with World Cup winner Zinedine Zidane.
Paris St Germain announced Christophe Galtier as their new manager on Tuesday, shortly after the Ligue 1 champions parted ways with Mauricio Pochettino.
Galtier joins PSG after leaving Nice last month, having guided them to a runners-up finish in the French Cup and fifth place in Ligue 1 last season.
The 55-year-old Frenchman joined Nice in 2021 after leading Lille to their first Ligue 1 title since 2011 in the previous campaign. Before joining Lille, Galtier spent eight seasons at Saint Etienne, where he won the French Cup in 2012-2013.
Galtier's appointment comes after PSG president Nasser al-Khelaifi put an end to speculation surrounding France great Zinedine Zidane, dismissing reports that PSG had been in talks with the 1998 World Cup winner about becoming their new boss.
Pochettino, who was appointed by PSG in January 2021, won the Ligue 1 title in 2021-22 and the French Cup in 2020-21 but failed to deliver in the Champions League, the only major trophy that has eluded PSG since Qatar Sports Investment took over in 2011.
PSG, eight times league winners since the takeover, were Champions League runners-up in 2020 but they were knocked out in the last 16 last season by eventual champions Real Madrid.
Pochettino came in with a strong resume after making Tottenham Hotspur perennial top-four finishers in England's Premier League and guiding them to the Champions League final in 2019.
Despite having a star-studded squad at his disposal at PSG, with Kylian Mbappe, Neymar and Lionel Messi leading the attack, Pochettino failed to win the other domestic trophies on offer, lifting only the league title last season.
Pochettino leaves PSG after 84 competitive games in charge, having won 55, drawn 15 and lost 14.