Bridges campaigned on a platform of generational change after former prime minister Bill English, 56, announced earlier this month that he was leaving the conservative party.
National had faced calls to revamp its leadership after losing last year's general election to the centre-left Labour Party, led by 37-year-old Jacinda Ardern.
The son of a Baptist minister, Bridges has described his family as "deeply religious" and he unsuccessfully voted against allowing gay marriage in 2013.
"It's a part of what makes me and I hope Maori New Zealanders see that and are excited about that," he said.
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"It shows them that actually they can achieve and they can do interesting things with their lives and there's a lot of opportunity in this country."
Bridges won a leadership ballot of National's 56 lawmakers by an undisclosed majority, with Paula Bennett retaining her position of deputy leader.
He said he would hold Ardern and her government to account, accusing it of "muddling along".
"That's why we will continue to present an ambitious and strong alternative government, heading into 2020 (elections)."
Bridges, a former prosecutor, was elected to parliament in 2008 and had stints as communications, economic development and transport minister when National was in office.