Aziz Akhennouch, a technocrat in his 50s who headed the ministry of agriculture and fisheries in the two previous governments, was appointed to the key cabinet post, the official MAP news agency reported.
He replaces Nizar Baraka, whose Istiqlal party withdrew from the ruling coalition in July after strongly criticising the Islamic Party of Justice and Development (PJD) for failing to shore up the economy and solve pressing social problems.
Morocco's government has been hamstrung since May when Istiqlal first announced its intention to withdraw from the PJD-led coalition, which won the largest share of votes in parliamentary elections two years ago.
Prime Minister Abdelilah Benkirane has been negotiating in recent weeks with the National Rally of Independents party, to which Akhennouch formerly belonged, to form a new cabinet and avoid early elections.
Morocco's economic problems are among the biggest challenges facing the ruling Islamic, who have struggled to push through much-needed reforms, notably on costly subsidies, to fix the country's ailing finances.