Apolinario was born on July 23, 1864 to Inocencio Mabini and Dionisia Maranan of Talaga, Tanauan, Batangas.

In Manila he won a partial scholarship in 1881 that enabled him to enroll at the College of San Juan de Letran. He worked as a teacher of Latin in Lipa but completed his Bachelor of Arts in 1887. In working for his Law degree at the University of Santo Tomas from 1888 to 1894, he supported himself by teaching and working as a copyist in the court of first instance in Manila and later as an assistant to law clerk Numeriano Adriano and as a clerk in the Intendencia General.

He joined the Masonry on September 1892 and adopted the name Katabay. In 1893, he was one of those who revived the La Liga to extend moral and financial support to the Reform Movement in Spain. The Cuerpo de Compromisarios emerged in September 1894 with the dissolution of the Liga.

In 1885 he was admitted to the bar and worked as a notary in the office of Adriano. On October 10, 1896 he was arrested because of his connection to the reformists but since both his legs were paralyzed due to polio, he was placed under house arrest at the San Juan de Dios Hospital. He was not able to participate in the first part of the Revolution due to his physical condition. In April 1898 he wrote a manifesto addressed to the revolutionary leaders wherein he analyzed the probability of the cession of the Philippines to the United States in case Spain was defeated in the Spanish American War. He exhorted them to preserve the country and its independence. It must have been this document that was received by the Hongkong Junta headed by Felipe Agoncillo who, impressed by the logical views presented, recommended the author to General Aguinaldo as his adviser upon his return to the Philippines from exile.

When Aguinaldo returned to the Philippines on May 19, 1898, he sent runners to Laguna to fetch Mabini and to carry him in a hammock to Cavite. After the intial meeting on June 12, 1898, Mabini became the indispensable adviser to Aguinaldo on indispensable state matters.

Significant achievements of Mabini were: the abolition of the Dictatorship of Aguinaldo government and its conversion into a revolutionary government, the organization of the municipalities, provinces and judicature and the police force; the establishment of the civil registry of property; the issuance of regulations for military procedure and the ultimate policies of government as were embodied in Aguinaldo’s decree dated June 23, 1898. He served the Aguinaldo cabinet as President of the Council of Secretaries and Secretary of foreign Affairs. He penned most of Aguinaldo’s decrees to the people and he wrote the El Verdadero Decalogo to arouse the patriotic spirit of the people.

When the Filipino American war broke out, he fled to Nueva Ecija but was captured by the Americans in Cuyapo on December 10, 1898. He was kept a prisoner of war until September 23, 1900. He resided in a small nipa house in Nagtahan and earned his living by writing for local newspapers. His virulent article in El Liberal entitled “El Simil de Alejandro” caused his rearrest and deportation to Guam. During his exile, he wrote the La Revolucion Filipina. Reluctantly he took the oath of allegiance to the United States and was returned to the Philippines on February 26, 1902. Though he was offered a high government position, he turned it down preferring to retire to his humble residence in Natahan.

He died on May 13, 1903 of cholera.