Najib was unopposed as president of the long-ruling United Malays National Organisation (UMNO) in the party's polls, the final results of which were tallied late Saturday. (Agencies)
However, other posts were closely watched to determine whether Najib was losing ground to powerful conservatives upset with his earlier pledge to liberalize a controversial system of preferences for the Muslim Malay majority, and other reforms.
Analysts said that Najib appeared to have held off conservatives, for now.
"On the surface of it, Najib's leadership of the party is undisputed," said Ibrahim Suffian, director of leading polling organisation Merdeka Center.
"His team will be able to push some reforms, but the right-wing element of the party is not extinguished. There will have to be some compromise."
The Barisan Nasional (National Front) coalition, through which UMNO has ruled the multi-ethnic, Muslim-majority country for decades, has won national elections by diminishing margins as voters tire of its race-based politics and authoritarian rule.
Najib, now 60 and in office since 2009, responded by advocating political and economic reforms to win back support, but has been restricted by hardliners keen to protect Malay dominance.
Najib has already backtracked on key reform moves including a cautious pledge to water down UMNO's decades-old affirmative-action policies for Malays in education, housing, and economic opportunities.
The system is resented by the sizeable ethnic Chinese and Indian minorities and economists view it as a drag on national competitiveness.
Najib was unopposed as president of the long-ruling United Malays National Organisation (UMNO) in the party's polls, the final results of which were tallied late Saturday.