In 1856, poverty led his parents to entrust him to the care of Augustinian priests in Intramuros, Manila who discovered his talent for music.

Under the friars, he was provided with daily sustenance, proper education, and access to musical environment but was also subjected to strict and harsh discipline.

Samples of his early works such as "Benedictus" and "Libera me, Domine" which were meant for performance at San Agustin were reportedly sent to Spain for expert evaluation.

In 1885, he had been elected record keeper of the newly founded Union Artistico Musical, one of the first organization of professional musicians in the colony.

[2][8] One of his students was a prominent businessman and music patron Francisco L. Roxas, who will later on be executed for treason during the Philippine Revolution.

[8] He also encouraged and recognized the musical talent of noted violinist Ernesto Vallejo, whom Adonay gifted his first violin.

[9] During the Philippine Revolution, Adonay's work "Te Deum", which is meant to be played in a mass of thanksgiving for victory in battle, was first performed on July 7, 1897.

A letter written to Emilio Jacinto by a musician named Guillermo Lisboa y Bagayan in Longos on January 15, 1899, mentioned Marcelo Adonay's arrangement of "Marcha Real Filipina" with instruction that it will be played when the Katipunan enters Manila.

At the funeral of zarzuela and soprano singer Maria Evangelista Carpena on March 8, 1915, he was tasked to conduct "Libera me, Domine".

In his golden wedding anniversary on January 17, 1924, he sponsored a composition competition which was won by a University of the Philippines professor Nicanor Abelardo.

Atanacio, one of his siblings, lived in the couple's Malate home nearly all his professional career life and would later on replace his brother as the organist of San Agustin Church upon Adonay's retirement in 1914.

His home altar was framed by a large oil painting of St. Cecilia willed by his student Francisco Roxas after his execution during the Philippine Revolution.

In his golden wedding anniversary on January 17, 1924, he sponsored a composition competition which was won by a University of the Philippines professor Nicanor Abelardo.

His experience with the illness was the inspiration for his humorous 1912 work "Ang Quirot ng Rayuma", for violin, cello, and harmonium.