He enrolled into a cadet institute at Hainburg in 1865, and, after spending some time there and at the academy in Znaim, he moved to a military academy in Vienna. He passed the courses at the academy with fair success and received an accelerated promotion to captain.
Kovess failed his examinations for promotion to the grade of major in the General Staff, and he then turned to the infantry; rapid promotions followed to major general in 1902, inspector of Tyrolean fortifications in 1910, and chief of the XII Army Corps and commanding general in Hermannstadt, Transylvania, in 1911. But once again qualification reports negated his talents, and Kovess was scheduled to retire late in 1914 owing to lack of offensive spirit.
Instead, the outbreak of war confirmed his command of the XII Corps, which he led into east Galicia, taking up positions south of Przemysl in October 1914. While junior generals such as Baron Eduard Bohm-Ermolli, Count Viktor Dankl, and Svetozar Boroevic were given command of armies, Kovess continued to head the XII Corps; late in 1914 he became involved in the general rout of Austro-Hungarian forces at Lemberg, and spent the winter months defending Silesia as part of General von Woyrsch's forces. Kovess' fortunes then turned for the better. During the breakthrough at Gorlice, he stormed the fortress Ivangorod on August 4, 1915, and, as commander of the Third Army attached to Army Group Mackensen, captured Belgrade on October 9, 1915. Kovess capped his string of successes in January 1916 by taking Montenegro; in February he conquered most of north and central Albania.
On May 15, 1916, Kovess led his Third Army as part of General Conrad von Hotzendorf's design to sweep down upon the Italians from the high plain of Lavarone-Folgaria and to capture the key rail center of Padua. Kovess managed to take Asiago, but stiff enemy resistance, the difficulty of terrain, and General Aleksei Brusilov's offensive in the east forced cancellation of the Tyrolean operation; Kovess was hastily sent back to Galicia. In October 1916, he was placed in charge of the Seventh Army in Marmaros-Sziget. Kovess helped to drive the Russians from east Galicia in the summer of 1917, and in August liberated the Bukovina and Czernowitz. Emperor Charles promoted him field marshal in August 1917 and raised him into the Hungarian baronage.
From January to April 1918, Kovess headed an army group comprised of the First and Seventh Army spanning the eastern front from Kronstadt to Czemowitz, but the conclusion of a separate peace with Russia in March left him temporarily unemployed. At a crown council on September 27, 1918, General Arz von Straussenburg suggested the formation of an army group, "West Balkans," under Kövess along the line Danube-Save-Drina in order to stem the Entente advance from the southwest in the wake of Bulgaria's collapse. Mass desertions by various ethnic formations rendered this proposal unfeasible. Kövess, as senior commanding general, was given supreme command of the army on November 3, 1918, by then an utterly meaningless appointment. He died in Vienna on September 22, 1924.
Kövess' father was a senior military officer living in Temesvár, Austrian Empire (now Timișoara, Romania). His mother's family belonged to the small German-speaking Transylvanian Saxon minority known as the Siebenbürger-Sachsen. He married the Baroness Eugenie Hye von Glunek in 1892 and they had 3 sons; Adalbert, who was killed in action in 1914 and Géza and Jenő who served as artillery officers.