The Philippine Republic (Spanish: República Filipina), retroactively known as the First Philippine Republic or the Malolos Republic, was a state established in Malolos, Bulacan, during the Philippine Revolution against the Spanish Empire (1896–1898) and the Spanish–American War between Spain and the United States (1898) through the promulgation of the Malolos Constitution on January 23, 1899, succeeding the Revolutionary Government of the Philippines. It was formally established with Emilio Aguinaldo as president. It was unrecognized outside of the Philippines but remained active until April 19, 1901. Following the American victory at the Battle of Manila Bay, Aguinaldo returned to the Philippines, issued the Philippine Declaration of Independence on June 12, 1898, and proclaimed successive revolutionary Philippine governments on June 18 and 23 of that year.

In December 1898, Spain and the United States signed the 1898 Treaty of Paris, ending the Spanish–American war. As part of the treaty, Spain ceded the Philippines to the United States. The treaty was not formally proclaimed until April 11, 1899, when mutual ratifications were exchanged. In the meantime, on January 23, 1899, the Malolos Constitution establishing the First Philippine Republic had been proclaimed and, on February 4, 1899, fighting had erupted in Manila between American and Filipino forces in what developed into the Philippine–American War. Aguinaldo was captured by the American forces on March 23, 1901, in Palanan, Isabela, he declared allegiance to the U.S. on April 19, 1901, effectively ending the Philippine Republic.

The First Philippine Republic is sometimes characterized as the first proper constitutional republic in Asia, although there were several Asian republics predating it – for example, the Mahajanapadas of ancient India, the Lanfang Republic, the Republic of Formosa, or the Republic of Ezo. Aguinaldo himself had led a number of governments prior to Malolos, like those established at Tejeros and Biak-na-Bato which both styled themselves República de Filipinas ("Republic of the Philippines"). Unlike the founding documents of those governments, however, the Malolos Constitution was duly approved by a partially elected congress and called for a true representative democracy.

In 1896, the Philippine Revolution began against Spanish colonial rule. In 1897, Philippine forces led by Aguinaldo signed a ceasefire with the Spanish authorities and Aguinaldo and other leaders went into exile in Hong Kong. In April 1898, the Spanish–American War broke out. The U.S. Navy's Asiatic Squadron, then in Hong Kong, sailed to the Philippines to engage the Spanish naval forces. On May 1, 1898, the U.S. Navy decisively defeated the Spanish Naval force and blockaded Manila Bay. The American naval commander, lacking forces to conduct land operations following his unexpectedly complete victory, returned Aguinaldo and a number of other revolutionary exiles to the Philippines from Hong Kong.

Aguinaldo arrived in the Philippines on May 24 and on that date, proclaimed a dictatorial government, rekindling the Philippine Revolution (formally established by decree on June 18). On June 12, he issued the Philippine Declaration of Independence from Spain at his ancestral home in Cavite. He established a revolutionary government on June 23, under which the partly-elected and partly-appointed Malolos Congress convened on September 15 to write a constitution.

On December 10, 1898, the 1898 Treaty of Paris was signed, ending the Spanish–American War and transferring the Philippines from Spain to the United States.

The constitution written by the Malolos Congress was proclaimed on January 22, 1899, creating what is known today as the First Philippine Republic, with Aguinaldo as its president. The constitution was approved by delegates to the Malolos Congress on January 20, 1899, and sanctioned by Aguinaldo the next day. The convention had earlier elected Aguinaldo president on January 1, 1899, leading to his inauguration on January 23. Parts of the constitution gave Aguinaldo the power to rule by decree. The constitution was titled "Constitución política", and was written in Spanish.

When the First Philippine Republic was constituted on January 22, 1899, in Malolos, that municipality became the seat of government of the Philippine Republic, and was serving as such when hostilities erupted between U.S. and Filipino forces in the Second Battle of Manila on February 4. On February 4, 1899, armed conflict erupted in Manila between Philippine Republic forces and American forces occupying the city subsequent to the conclusion of the Spanish–American War. That day President Aguinaldo issued a proclamation ordering and commanding that "peace and friendly relations with the Americans be broken and that the latter be treated as enemies, within the limits prescribed by the laws of war". The fighting quickly escalated into the Second Battle of Manila, with Philippine Republic forces being driven out of the city. American forces pushing north from Manila after the outbreak of fighting captured Caloocan on February 10. On March 29, as American forces threatened Malolos, the seat of government moved to San Isidro, Nueva Ecija. On March 31, American forces captured Malolos, the initial seat of the Philippine Republic government, which had been gutted by fires set by withdrawing Philippine Republic forces. Emilio Aguinaldo and the core of the revolutionary government had by then moved to San Isidro, Nueva Ecija. Peace negotiations with the American Schurman Commission during a brief ceasefire in April–May 1899 failed, and San Isidro fell to American forces on May 16. The Philippine Republic core government had moved by then to Bamban, Tarlac, and subsequently moved to Tarlac town. Aguinaldo's party had already left Tarlac, the last capital of the Philippine Republic, by the time American troops occupied it on November 13.