Arroyo entered politics in the 1992 election, running for senator. At the first general election under the 1987 Constitution, the top twelve vote-getting senatorial candidates would win a six-year term, and the next twelve candidates would win a three-year term. Arroyo ranked 13th in the elections, earning a three-year term. She was re-elected in 1995, topping the senatorial election with nearly 16 million votes.
As a legislator, Arroyo filed over 400 bills and authored or sponsored 55 laws during her tenure as senator, including the Anti-Sexual Harassment Law, the Indigenous People’s Rights Law, and the Export Development Act.
The 1995 Mining Act, which allows 100% foreign ownership of Philippine mines, has come under fire from left-wing political groups.