Lam took over the duties of party chief on July 18, a day before Trong's death as his health was deteriorating.
Party delegates unanimously supported Lam's nomination, officials told a press conference on Saturday.
Addressing the delegates, Lam vowed to inherit and promote Trong's legacy, make no changes to the Southeast Asian nation's foreign policy, focus on achieving its socioeconomic development goals and "fiercely" continue Vietnam's anti-graft campaign.
Former Communist Party leader Nguyen Phu Trong died on July 19 after a 13-year reign. (AP PHOTO)
Vietnam does not formally have a paramount leader, but the head of the party effectively plays a more prominent role than others after Trong strengthened the powers of the role during his 13-year tenure.
Lam, a career security officer, had been seen as long aiming to become party chief, with experts calling the presidency a stepping stone for the top job.
He was elected president in May after leading a sweeping campaign of high-profile investigations against corruption as police minister.Â
He replaced Vo Van Thuong, who had been in the job about a year when he quit amid accusations of unspecified wrongdoing.
16°C