Bersatu president Muhyiddin Yassin took his oath of office as the eighth Prime Minister of Malaysia before the Yang di-Pertuan Agong Sultan Abdullah Sultan Ahmad Shah at Istana Negara.
The swearing-in took place at Balai Singgahsana Kecil (Minor Throne Room) at 10.33am.
Al-Sultan Abdullah appointed Muhyiddin as the new prime minister in accordance with Articles 40(2)(a) and 43(2)(a) of the Federal Constitution.
Dr Mahathir Mohamad had been the interim prime minister after resigning as the seventh prime minister on Feb 24.
Raja Permaisuri Agong Tunku Hajah Azizah Aminah Maimunah Iskandariah also graced the swearing-in ceremony.
Muhyiddin, 72, attired in a black baju Melayu and gold-embroidered black samping, was accompanied by his wife Noorainee Abdul Rahman.
After taking his oath, Muhyiddin signed the instruments of appointment, witnessed by Chief Justice Tengku Maimun Tuan Mat and Chief Secretary to the Government Mohd Zuki Ali.
Among the political leaders present were Umno president Ahmad Zahid Hamidi, PAS president Abdul Hadi Awang, MCA president Wee Ka Siong and Gombak MP Mohamed Azmin Ali.
Federal Territory mufti Zulkifli Mohamad Al-Bakri recited the doa.