Like Mr Badawi before him, Mr Najib comes to the job promising reforms
Najib Razak, regarded by many Malaysians as a political blue blood, has been groomed his entire political life for the premiership.
The son of the country's second prime minister and nephew of the third, Mr Najib entered parliament at the age of 23 and quickly rose to prominence.
He has held a host of cabinet posts including finance and defence. His most recent position was that of deputy to the outgoing Prime Minister Abdullah Badawi.
Now aged 55, Malaysia's sixth post-independence leader has pledged "massive changes", a more transparent government and basic freedoms for his people.
But Mr Najib takes the helm at a turbulent time, with Malaysia's economy deteriorating and its politics in turmoil. It is unclear if he will be able to deliver on his promises and ride out the storm.
Growing up, Mr Najib attended the renowned Malay College Kuala Kangsar before studying for a bachelor's degree in industrial economics in the UK.
As the eldest son of Abdul Razak Hussein, he learned the demands of mainstream politics early on. This helped his preparations for his election to parliament in 1976.
Mr Najib replaced the moderate and largely ineffective Abdullah Badawi
Mr Najib became the youngest MP in Malaysian history after winning the Pekan constituency in his home state of Pahang, when it became vacant after the death of his father.
A year later he became the youngest deputy minister and aged 29, Pahang's chief minister.
He was appointed a full minister in 1987, and moved quickly through the political hierarchy.
In March, Najib Razak was installed as the uncontested leader of the United Malays National Organization (Umno), the main party in the coalition that has governed Malaysia since 1957.
This appointment guaranteed him the post of prime minister.
But Mr Najib's path to the top has not been without its problems.
He has been accused of benefiting financially from various defence deals, and he has also faced allegations linking him to a murder scandal.
Mr Najib has strongly denied all the claims against him, but his opponents show no sign of letting these allegations die away.
'Renewal and regeneration'
As prime minister, Mr Najib replaces Abdullah Badawi who, during six years in office, made little progress in efforts to end political corruption, liberalise the economy and reform the judicial system.
The unpopular Mr Abdullah also led Umno to its worst election result in 50 years last year, only narrowly keeping its grip on power.
In his farewell address to party members, Mr Badawi warned that the party would perish if it continued to silence critics and discriminate against minority Chinese and Indian races.
Like Mr Badawi before him, Mr Najib comes to the job promising reforms. Facing a revitalised opposition, Mr Najib also seems to acknowledge that Malaysians want something new.
"Economic progress and better education have directly resulted in the birth of a class of voters who are better informed, very demanding and highly critical," he told an Umno party conference.
"If we do not heed this message, their seething anger will become hatred and in the end this may cause them to abandon us altogether."
But his ascension to power has been marked by a recent government crackdown on Umno's political opponents and on free speech.
If voters don't see any improvement, they may decide to take it out on Mr Najib at the ballot box.