He will be sworn in at 5pm local time (0900 GMT), said King Sultan Abdullah Sultan Ahmad Shah.
Mr Ibrahim’s Alliance of Hope led Saturday’s election with 82 seats. It, however, fell short of the 112 needed for a majority. Former prime minister Muhyiddin Yassin’s right-leaning National Alliance won 73 seats, with its ally Pan-Malaysian Islamic Party emerging as the biggest single party with 49 seats.
Mr Ibrahim emerged victorious after other smaller blocs agreed to support him for a unity government. His rise to the top will ease anxieties in the multiracial nation over greater Islamization under Mr Yassin and spark hope that reforms for better governance will resume.