Upon the Russian entry into World War I Romanovsky was named chief of staff of the 25th Infantry Division. For action during the Russian invasion of East Prussia he was awarded the Order of St. George in 1914. In August 1915 he was appointed commander of the 206th Infantry Regiment, part of the 52nd Infantry Division. From June to October 1916 he served as chief of staff of the 13th Army Corps. From October 1916 to March 1917 he was quartermaster general for the 10th Army before becoming chief of staff for the 8th Army under Lavr Kornilov, who Romanovsky would follow as a staff officer when Kornilov became Supreme Commander-in-Chief of the Provisional Government's armed forces. From July to September 1917 he served as Chief of the General Directorate of the General Staff.