The Senator of the Philippines knocked out Argentine Lucas Matthysse in the seventh round to win the title.
Following the 60th win of his career, the 39-year-old tweeted: "To God be the glory! Thank you to my wife, my kids, and all ofmy family. Thank you to #TeamPacquiao for all your hard work! Thank you to my fellow Filipinos and to all my fans around the world! This is all our victory. God bless everyone."
His latest win was his first knockout since stopping Miguel Cotto in November 2009.
Pacquiao has been very open about his Christian faith.
To God be the glory! Thank you to my wife, my kids, and all of my family. Thank you to #TeamPacquiao for all your hard work! Thank you to my fellow Filipinos and to all my fans around the world! This is all our victory. God bless everyone. pic.twitter.com/UdZ78XI5CD
— Manny Pacquiao (@mannypacquiao) July 15, 2018
He told the Guardian: "I have a lot of dreams and visions. I even heard the voice of God. When I heard the voice of God, I am trembling and melting. I feel I have died. It was an amazing, amazing experience.
"I'm happy because I found the right way, salvation, born again. We are required to be born again, all of us.
"Christ said unless we are born again we cannot enter the kingdom of God. So it's very important to me."
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