The plant, due to open in 2019 north of Rabat, will cater for "the needs of the region and of Moroccan customers," a statement said.
Chairman Carlos Tavares signed an official agreement with Industry Minister Moulay Hafid El Alamy in the presence of King Mohamed VI at his palace in the capital, an AFP journalist said.
The group said the plant "will by 2019 assemble engines and vehicles in the B and C segments" -- compact and mid-sized cars, the mainstay of Morocco's automobile industry.
Alamy said the new factory would create 4,500 full-time and provide indirect employment for up to 20,000 workers.
PSA said it was "today preparing the conditions to realise its commercial ambition (to produce) a million vehicles in the Middle East and Africa region by 2025".