Irro was born in the southern town of Kismayo, Somalia, to a Majeerteen Harti Darod family. As a young man, his father Ahmed Yussuf Irro and two of his uncles had served in the Italian colonial army. They were among the men forcibly conscripted after the fall of the ruling northern Majeerteen Sultanate (Migiurtinia) and Sultanate of Hobyo (Obbia) during the Fascist-period Campaign of the Sultanates, an expedition which lasted from 1921 to 1929 under the command of Cesare Maria De Vecchi. Irro's mother, Dahabah, was the daughter of a wazir of the Hobyo Sultanate..
Irro spent the better part of his adolescence in Mogadishu, where he was educated in Italian primary and secondary schools. He subsequently studied at the local two-year teacher's training Instituto Universario Della Somalia, graduating with honours. Following the completion of his studies, Irro worked for a few years in the late 1950s as an instructor.
After Somalia obtained its independence in 1960, Irro joined the nascent Somali National Army (SNA), becoming the force's 32nd officer.
Irro received military instruction at the Egyptian Military Academy in Cairo, Egypt in 1961. He graduated from the college with a Bachelor's degree in Military Sciences. Irro subsequently returned to Somalia i where he worked in the office of the central command and the directorate of planning under [[Dauud]] , [[Siad Barre]], [[Mohamed Ali Samatar]] and [[Abdullah Mohamed Fadil] .
Irro along with other left-leaning comrades was later admitted to the Frunze Military Academy in Moscow (Военнаяакадемия им М. В. Фрунзе), an elite Soviet institution reserved for the most qualified officers of the Warsaw Pact armies and their allies. There, he specialized in Strategic Planning and wrote many articles on strategy, operations and contemporary warfare, with an emphasis on Proactive National Defense. Irro published several works in Arabic and Russian analysing conventional warfare in Africa, Asia and Latin America, but focused in particular on the various strategies employed during the Sino-Indian War of 1962 and the Indo-Pakistani conflicts of 1965 and 1971. Irro eventually completed the rigorous staff-level training at Frunze, and later received the highest military doctoral degree (кандидат наук). Other Somali graduates from the military institution included Salaad Gabeyre Kediye, Abdullahi Yusuf Ahmed and Abdullah Mohamed Fadil.
Upon returning to Somalia, Irro occupied various posts in the Somali National Army. He mainly served as a non-political officer in the planning and operations sector, heading the directorate of planning in addition to similar positions in the 21st and 60th Divisions. Irro worked his way up the SNA, obtaining the rank of Colonel. During the 1970s, he was the Commandant (Abaanduule) of the army's 60th Division.
Under the leadership of colleagues and fellow Frunze graduates Generals Mohamed Ali Samatar and Abdullah Mohamed Fadil, Irro and other senior Somali military officials were mandated in 1977 with formulating a national strategy in preparation for the Ogaden campaign in Ethiopia. This was part of a broader effort to unite all of the Somali-inhabited territories in the Horn region into a Greater Somalia (Soomaaliweyn).
Colonel Abdullahi Irro commanded the SNA units in the Godey Front, seizing the area on July 24, 1977. Godey was guarded by the Ethiopian Army's 4th Division, which was based in five local military bases. The 60th division forces under Col Irro consisted of 2nd Armoured Brigade equipped with T-54 MBTs, Infantry as well as an Artillery Brigade 36 artillery and Tank Battalion equipped with T-34 MBTs.
Under Irro's leadership, Somalia's 60th Division brigades succeeded in defeating the 4th Ethiopian Division in Godey, causing it to collapse and cease to exist altogether as a functional force. Godey's capture also allowed the Somali side to consolidate its hold on the Ogaden, concentrate its forces, and advance further to other regions of Ethiopia. Units from Somalia's 60th occupied Haile Salase's Emperial Palace where they captured senior Ethiopian officer among them the founding father of Ethiopia's Airforce the Swedish aviator Carl Gustaf von Rosen.
Following this successful operation at Godey, Irro was appointed Chief Commanding Staff Officer in the 60th Division. He was assigned organization and mobilization duties vis-a-vis various army brigades in the Southern Divisions, including six infantry brigades destined for Nagele, beyond Godey towards Bali and Sidamo. Irro was also tasked with supplying logistical and technical support, part of the southern command's contingency plans. In doing so, he was facing off against former Frunze Professor, Vasily Ivanovich Petrov, who was the Red Army General assigned to assist and rebuild the Ethiopian Army.
In spite of unreserved support by Cuba and The Union of Soviet Socialist Republics, it took nearly three years for the Ethiopian Army to gain a full control of the Godey region. Brigadier-General Demisse Bulto, commander of the First Revolutionary Army, recovered Godey as part of Operation Lash by November 1980, nearly three and half years since the Somali Army occupied it in July 1977. Ethiopia's Derg regime would later execute Bulto for his involvement in a failed coup d'état in Ethiopia in 1989.
In late 1979, at the recommendation of the national Ministry of Defense, Irro was awarded the Somali Medal of Valor by President Barre. The medal was issued in recognition of Irro's various contributions to the Military of Somalia. In the years that followed, he went on to become a General in the Somali National Army.
In 1978, fallout from the aborted Ogaden campaign culminated in an attempt by several Somali senior military officials to overthrow Siad Barre's administration. According to the memoir of the late Colonel Abdullahi Yusuf Ahmed, Irro informed him via a secured communication network that the coup d'état had failed. The transmitted communication contained a coded two sentence message reading "Wife Aborted", dated 11:00 am, April 9, 1978. Irro was arrested a few hours later by the ruling government of President Barre under suspicion of participation in the putsch. Most of the people who had helped plot the coup were found guilty and executed by marshal court; but others, including fellow Frunze Military Academy graduate Colonel Ahmed, managed to escape abroad. The coup leader Colonel Mohamed Osman Irro was arrested and executed. His Colleague Colonel Abdullahi Irro was arrested and released after Marshall court found no evidence of collaboration with Mohamed Osman Irro
Abdullahi Irro later served as a Professor of Strategy at various Somali Military Institutes in the 1980s. In this capacity, he helped put together the National Academy for Strategy, and had a hand in formulating strategic training syllabi earmarked for military personnel and legislators. He also played a leading role in forging working partnerships with several schools in Egypt (1983), France (1984) and the United States (1984)
A polymath, Irro remained politically neutral throughout his adult life. He declined various offers to join opposition groups that had begun to form in the wake of the Ogaden campaign, including the Somali Salvation Democratic Front (SSDF), Somali National Movement (SNM) and United Somali Congress (USC) led by his former comrades Abdullahi Yusuf Ahmed, Abdulkadir Koosaar and Mohamed Farrah Aidid, respectively.
General Irro lives in Vienna, Virginia and occasionally participates in efforts to create peaceful society in Africa. He was one of 30 senior Somali officials invited by the UN to advise the United Nations. Irro and his colleagues provided a framework document to address strategies for both short-term security challenges and longer-term capacity building measures. Medal of Valor, Somali Democratic Republic (1979)