Teodoro Sandiko was born in the district of Pandacan, Manila on March 31, 1860 to Miguel Sandiko and Maria Paz Santa Ana.
He first learned his alphabet at home and began his formal education under Capitan Manuel de Pandacan, then continued his first second years in Latin lessons at the school of Vicente Quirino. He pursued his third year studies in the school of Quintin Salvidea and his fourth year under the Jesuits in Manila. Subsequently, he transferred to the University of Santo Tomas where he obtained his Bachelor of Arts in 1886. He had two years of law, but he opted to concentrate on teaching Latin in a school of Malolos rather than finish the course.
With his progressive ideas, he incurred the ire of the Spaniards, particularly of the ecclesiastical authorities and to escape persecution, he left for Hongkong and proceeded to Spain where he continued his law studies at the University of Madrid. He managed La Solidaridad, a patriotic newspaper founded by Graciano Lopez Jaena on February 15, 1889, which later became the mouthpiece of the Filipino propaganda movement.
In the Revolutionary Government of General Emilio Aguinaldo, he held various positions: Director of the Secretaria de Relaciones Exteriores, colonel of the Estado Mayor and brigadier general of the Revolutionary government.
He resigned from his job and became Secretary of Interior on January 2, 1899 and General of the First Philippine Republic. He entered politics and was twice elected governor of Bulacan and attended the first conventions of governor’s in Manila on October 23, 1906.
He was elected Senator representing the third senatorial district comprising the province of Tarlac, Nueva Ecija, Pampanga and Bulacan from 1919 to 1931. As a Senator he became popular in the Senate for his political conviction and was dubbed “ Constructive Oppositionist” and he became a member of the commission for independence in 1921 and 1922.
During the 1934 to 1935 Constitutional Convention, he was elected delegate of the first district of Bulacan and elected Second Vice-President on July 1934 at the House of Representatives.
After retiring from public life he became the manager of two cigas factories: Katubusan and La Paz y Buen Viaje.
He died on October 19, 1939.