The Senate of the Philippines (Filipino: Senado ng Pilipinas) is the upper house of Congress, the bicameral legislature of the Philippines, with the House of Representatives as the lower house. The Senate is composed of 24 senators who are elected at-large (the country forms one district in senatorial elections) under a plurality-at-large voting system.

Senators serve six-year terms with a maximum of two consecutive terms, with half of the senators elected in staggered elections every three years. When the Senate was restored by the 1987 Constitution, the 24 senators who were elected in 1987 served until 1992. In 1992, the 12 candidates for the Senate obtaining the highest number of votes served until 1998, while the next 12 served until 1995. This is in accordance with the transitory provisions of the Constitution. Thereafter, each senator elected serves the full six years. From 1945 to 1972, the Senate was a continuing body, with only eight seats up every two years.

Aside from having its concurrence on every bill in order to be passed for the president's signature to become a law, the Senate is the only body that can concur with treaties and try impeachment cases. The president of the Senate is the presiding officer and highest-ranking official of the Senate. They are elected by the entire body to be their leader and are second in the Philippine presidential line of succession. The current officeholder is Vicente Sotto III.

The Senate has its roots in the Philippine Commission of the Insular Government. Under the Philippine Organic Act, from 1907 to 1916, the Philippine Commission headed by the governor-general of the Philippines served as the upper chamber of the Philippine Legislature, with the Philippine Assembly as the elected lower house. At the same time the governor-general also exercised executive powers.

In August 1916 the United States Congress enacted the Philippine Autonomy Act or popularly known as the "Jones Law", which created an elected bicameral Philippine Legislature with the Senate as the upper chamber and with the House of Representatives of the Philippines, previously called the Philippine Assembly, as the lower chamber. The governor-general continued to be the head of the executive branch of the Insular Government. Senators then were elected via senatorial districts via plurality-at-large voting; each district grouped several provinces and each elected two senators except for "non-Christian" provinces where the governor-general of the Philippines appointed the senators for the district.

Future president Manuel L. Quezon, who was then Philippine Resident Commissioner, encouraged future president Sergio Osmeña, then Speaker of the House, to run for the leadership of the Senate, but Osmeña preferred to continue leading the lower house. Quezon then ran for the Senate and became its president serving for 19 years (1916–1935).

This setup continued until 1935, when the Philippine Independence Act or the "Tydings–McDuffie Act" was passed by the U.S. Congress which granted the Filipinos the right to frame their own constitution in preparation for their independence, wherein they established a unicameral National Assembly of the Philippines, effectively abolishing the Senate. Not long after the adoption of the 1935 Constitution several amendments began to be proposed. By 1938, the National Assembly began consideration of these proposals, which included restoring the Senate as the upper chamber of Congress. The amendment of the 1935 Constitution to have a bicameral legislature was approved in 1940 and the first biennial elections for the restored upper house was held in November 1941. Instead of the old senatorial districts, senators were elected via the entire country serving as an at-large district, although still under plurality-at-large voting, with voters voting up to eight candidates, and the eight candidates with the highest number of votes being elected. While the Senate from 1916 to 1935 had exclusive confirmation rights over executive appointments, as part of the compromises that restored the Senate in 1941, the power of confirming executive appointments has been exercised by a joint Commission on Appointments composed of members of both houses. However, the Senate since its restoration and the independence of the Philippines in 1946 has the power to ratify treaties.

The Senate finally convened in 1945 and served as the upper chamber of Congress from thereon until the declaration of martial law by President Ferdinand Marcos in 1972, which shut down Congress. The Senate was resurrected in 1987 upon the ratification of the 1987 Constitution. However, instead of eight senators being replaced after every election, it was changed to twelve.