Nepal's 601-seat Constituent Assembly approved the constitution on Wednesday with a 507-25 vote. The vote was boycotted, however, by smaller opposition parties that account for 9 percent of the assembly.
The new charter comes after years of disagreement between the main political parties and is Nepal's first constitution to be written by elected representatives. The six previous constitutions were instead drafted by boards of crown-appointed experts.
Nepal was required to draw up the new constitution under the 2006 Comprehensive Peace Accord, which brought an end to the decade-long Maoist insurgency. More than 17,000 people died in the conflict. For the past nine years, the country has had an interim constitution.
The approval of the charter on Wednesday follows weeks of demonstrations in southern Nepal where ethnic minorities have been protesting against a clause that decrees the division of the country into seven federal states.
Some ethnic groups disagree with the borders and sizes of the provinces, however, and are demanding a model which ensures then greater autonomy.
More than 40 people have died in the clashes between protesters and security forces.
The new constitution will be officially declared by President Tam Baran Yadav on Sunday.
Saudi diplomat in Nepalese maid rape case
India announced late on Wednesday that Saudi Arabia had withdrawn a diplomat accused of repeatedly raping and torturing two Nepalese maids.
A statement released by New Dehli said the diplomat was protected under the Vienna Convention on Diplomatic Relations, which grants diplomats immunity from arrest, criminal prosecution, and civil lawsuits while posted overseas.
The two Nepali women, aged 30 and 50, told police that recruiting agents lured them from their homes in Nepal under the promise of higher wages. Police rescued the women last week after a third maid saw their condition and informed a local non-governmental organization (NGO).
The charges have created diplomatic tensions between Saudi Arabia and India ahead of Indian Prime Minister Narendra Modi's planned state visit to Saudi Arabia later this year.
Modi will seek to secure an investment from the rich, oil state and to expand in the energy sector. Improving India's relations with Nepal is also a priority for the prime minister.
kb/jil (Reuters, AFP, AP, dpa)