And in a sign that he will not enjoy a "honeymoon" period that many leaders do on taking office, the three parties forming the opposition alliance sent a joint petition to the king asking him to delay Najib's swearing-in over allegations of corruption and links to a murder case.
"Such an important post must be given to an individual who is clean and whose integrity is not questionable," said the petition.
But Mahathir Mohamad, who was prime minister for 22 years before handing the post to Abdullah, said Najib has a chance to exclude corrupt Umno leaders from his new cabinet.
"If he does that i think he will win back the support of the people," he told Al Jazeera.
The opposition has repeatedly accused Najib of corruption in a deal to buy French submarines when he was defence minister.
It has also alleged that he was linked to the killing of the Mongolian mistress of Najib's close former aide.
Najib has labelled the allegations as "malicious lies".
Azmi Sharom, a political analyst, told Al Jazeera that the Malay population has turned against Umno, the main coalition partner in the country's ruling barisan Nasional (National Front) led by Najib.
"The reason for this is because Umno on the one hand makes a lot of noise about how they are the champions of the Malay race ... and yet on the other hand practice corruption and nepotism," he said.
Azmi says the ruling party instead of reacting in a positive way to give people the freedoms they are craving for, appears to be hanging on to power by taking the path of iron-fisted rule often associated with Mahathir.
"That is a very worrying sign ... and I have great fears about the immediate future of this country and where we are headed."
Abdullah, who took office in 2003, was pressed to step down following a dismal performance by the ruling Barisan Nasional (BN) coalition in last year's general elections.
The BN, which has been in power since independence in 1957, failed to maintain its two-thirds majority in parliament for the first time in 40 years, and also lost control of an unprecedented five states.
Despite insufficient proof critics say the scandals surrounding Najib have made the public lose faith in him.
"Najib is not even accepted by his own party as a man who can win back the Malays," Karpal Singh, a lawyer and opposition MP, told Al Jazeera.
"For one ... his credibility is far from acceptable."