The official results are still days away.
The Filipino boxer is thought to have won about 93% of precincts reporting.
That places him eighth among candidates for 12 Senate seats.
It puts him nearly 3 million votes ahead of the candidate in 13th place.
We don't need a reason to help people. It is God's commandment to us all to help those in need.#PacquiaoForSenator pic.twitter.com/uJ4fruM1K2
— Manny Pacquiao (@mannypacquiao) May 4, 2016
He cast his vote on Monday in his home area of southern Sarangani province.
He had bounced back in polls after losing support in February over remarks he made about same-sex marriage.
In February Filipino was accused of making a homophobic slur, he said homosexuals as "worse than animals" in a television interview.
He said: "It's common sense. Do you see animals mating with the same sex?''
"Animals are better because they can distinguish male from female.
"If men mate with men and women mate with women they are worse than animals," Pacquiao said when his comments were translated into English by TV5's Facebook page.
I'm sorry for hurting people by comparing homosexuals to animals. Please forgive me for those I've hurt. God Bless! pic.twitter.com/bqjRcWqp8R
— Manny Pacquiao (@mannypacquiao) February 16, 2016
Following the comments sportswear giant Nike has cut its ties with multi-weight world champion.
He apologised to people hurt by his comments, but made clear he opposed gay marriage.
