Ignacio Elizondo was born 9 March 1766 in the Salinas Valley, New Kingdom of Leon, New Spain, in the village of Salinas (now Salinas Victoria, Nuevo León, Mexico). He was the son of José Marcos de Elizondo and María Josefa de Villarreal. He was of Spanish and Basque ancestry. He was a New Leonese militia officer, mostly known for his successful plot capturing the most important leaders of the early Mexican War of Independence, including Miguel Hidalgo, Ignacio Allende, and Juan Aldama at Baján, Coahuila, in 1811.

During his childhood, Elizondo lived in the village of Pesquería Grande (present-day Garcia, Nuevo León). His father owned many ranch and agricultural properties then known as haciendas. In 1787, at the age of twenty-one he married María Gertrudis. She died on March 6, 1797, when she was giving birth to his son, José Rafael Eusebio.

Ignacio Elizondo started his military career in 1798, after being designated Lieutenant of Pesquería's provincial militia company. Two years later, he was honoured by being appointed Captain of Punta de Lampazos' provincial Dragoons, one of the largest military 'presidios' of the New Kingdom of León. However, one year later Elizondo occupied again his former position at the Pesquería's provincial militia. In 1806, governor Pedro de Herrera y Levya, recommended him for command of the Eighth Dragoons company, who would help Texas against recurrent Apache attacks, already present in northern towns of the New Kingdom of León. Through a letter to the viceroy Elizondo demanded that he be exempted from his military command position because of serious financial losses he was suffering in some of his ranches and stock properties, among some he had previously bought from the church. In the same letter, he expressed he was also suffering under reprisals from governor Pedro de Herrera, that would force his desertion. After falling out with Herrera, indebted with the purchase of several haciendas from the church, and marrying María Romana Carrasco the same year, he then decided to change his residency to the Hacienda of San Juan de Canoas, in the province of Coahuila, from where he also administered the Hacienda of Alamo, in the jurisdiction of Monclova.

Elizondo briefly left his military service prior to the Grito de Dolores and the outbreak of the Mexican War of Independence. In the Eastern Internal Provinces, the independence movement was not well received at first. Coahuila, Nuevo Santander, and Texas declared themselves for the royalists, but several towns eventually joined the cause. The governor of Nuevo León, Manuel de Santa María, eventually joined the rebels. Within Texas, Lt. José Menchaca and various filibuster expeditions acted to support the rebellion. Elizondo also joined the rebellion and commanded a small force in the Casas Revolt, in January 1811. However, Elizondo, vacillated in his support, marched through Nuevo León, Nuevo Santander and Texas for the royalists, confronting the Gutiérrez–Magee Expedition in San Antonio, at the Battle of Alazan Creek, in 1813. Governor Santa María was removed from his post for the royalist Simón de Herrera. Some historians debate whether General Ramon Díaz de Bustamante or Bishop Primo Feliciano Marín de Porras finally won Elizondo over to the royalists, while others believe, he was converted by Manuel María de Salcedo of Texas and Simón de Herrera of Nuevo León, while the royalist governors were his prisoners, during his participation in the Casas Revolt. He was instrumental in the capture of Father Hidalgo, General Allende, and other rebel leaders at the Wells of Bajan (Norias de Bajan) in February 1811, which effectively ended the first phase of the rebellion. On August 18, 1813, at the Battle of Medina, leading a cavalry division of the Royal Spanish Army under command of Commandant-General of the Eastern Internal Provinces, Joaquin de Arredondo, he played a key role in defeating the Republican Army of the North and crushing the Gutiérrez–Magee Expedition, as well as the insurrection in Texas

Elizondo's victory was praised by royalists, and even King Fernando VII, rewarded him with a promotion to Lt. Col. in the royalist army. However, his well-being didn't last too long, while returning from mopping-up operations in eastern-Texas (and having executed and imprisoning hundreds), he gained many enemies, hence hated by many insurgents, Ignacio Elizondo was critically wounded by one of his own aides, Lieutenant Miguel Serrano (who, it is said, had gone crazy from witnessing the scenes of merciless executions relentlessly carried-out by his commander over the preceding days), while sleeping in his tent at the edge of the Brazos River. Most historians aver that he was buried a few days later on the banks of the San Marcos River, in Texas, New Spain, where he expired, as he was being carried back to the capital on a litter. If Col. Elizondo was, indeed, first interred on the banks of the San Marcos River, where he expired on his return to San Antonio, then his remains must have been exhumed later and re-buried in San Antonio, where on 9 October 1815, his burial is recorded in the campo santo record book at San Fernando cathedral as No. 715: "Ignacio Elizondo, Lt. Col. of the cavalry. Spanish, married to Romana Carrasco. He died of wounds received in a fist fight."