Macapagal-Arroyo entered government service as an assistant secretary of the Department of Trade and Industry during the Aquino administration. She also became executive director of the Garments and Textile Board, steering the garments industry to become the top net dollar earner for the country, and rose to the rank of Undersecretary of Trade and Industry. In 1992, she was elected senator during her first try in politics and was reelected senator in 1995 with nearly 16 million votes, the highest number of votes in Philippine history. During her tenure in the Senate, she authored 55 laws on economic and social reform and was named outstanding senator several times.
On 11 May 1998, she was elected vice president of the Philippines with almost 13 million votes, the largest mandate in the history of presidential or vice presidential elections. Joseph Estrada, running under the Laban ng Makabayang Masang Pilipino (LaMMP—Fight of Nationalist Filipino Masses) banner, was the clear presidential victor, notwithstanding allegations of electoral fraud. He captured 46.4% of the vote in a 10-candidate contest. His nearest challenger was former speaker of the house, Jose de Venecia, who garnered only 17.1% of the vote. Macapagal-Arroyo was de Venecia's running mate, and in spite of de Venecia's defeat, won the vice presidency with 50.2% of the vote. Estrada's running mate, Edgardo J. Angara, finished a distant second with 24.5% of the vote.
President Estrada appointed Vice President Macapagal-Arroyo Secretary of Social Welfare and Development, a post she held until she resigned from the Cabinet on 12 October 2000. In October 2000, Estrada faced bribery charges of having accepted large sums of money from illegal gambling and tobacco taxes. When impeachment by the House appeared imminent, Arroyo resigned from the Cabinet, but stayed on as Vice President. In November 2000 Estrada was impeached by the House and in December five bombs exploded around Manila killing 22 people and injuring many more. Unwilling to wait for Senate deliberations, people took to the streets in a massive display of people's power reminiscent of 1986. Estrada resigned under intense popular pressure.
With Estrada's resignation, the Supreme Court unanimously declared the position of President vacant, and Macapagal-Arroyo was sworn in as the 14th President of the Philippines on 20 January 2001 by Chief Justice Hilario Davide Jr. She is the second woman after Corazon Aquino to be swept into the Presidency by a peaceful revolution of People's Power "EDSA II," now a Philippine trademark.