Lybeck was born on 19 February 1871 in Stockholm, Sweden, the son of Johan August Lybeck, a bank accountant, and his wife Emelie Carolina Sofia Klynder. Lybeck was a cadet at the Royal Swedish Naval Academy from 1886 and was commissioned as an officer in the Swedish Navy with the rank of underlöjtnant in 1892. He was promoted to sub-lieutenant in 1895, and undertook language studies in Russia from 1895 to 1897, after which he served as Russian language teacher in the Naval Staff before attending the Royal Swedish Army Staff College from 1898 to 1900. He then served in the Fleet Staff for four years, and advancing to the rank of lieutenant in 1901. In 1904, he was sent to East Asia to observe the Russo-Japanese War. He served as adjutant to the Inspector of the Navy's Exercises at Sea, captain Wilhelm Dyrssen from 1904 to 1907, and as teacher of naval organizational learning at the Royal Swedish Naval Staff College from 1905 to 1909 and of strategy from 1910 to 1918. Lybeck was naval attaché in Saint Petersburg from 1906 to 1911 and teacher of naval sciences at the Royal Swedish Army Staff College in 1908. Lybeck then served in the Naval Staff from 1909 to 1915. Several times nominated as councilor of the Naval Pension Fund, Lybeck was, due to his outstanding ability and great work ability, engaged for a variety of special assignments, such as assisting the 2nd Defense Preparation in 1914, secretary of the Defense Committee that same year, expert for special assignment within the Ministry of Civil Affairs in 1915, expert in the Ministry for Naval Affairs for an inquiry into wage regulation for the navy's personnel and for investigation concerning certain naval defense needs, member of the international commission in The Hague in 1917, chief arbitrator in the international commission in Berlin concerning the treatment of raised ships in 1917, expert in arbitration in Copenhagen concerning international law cases between Germany and Denmark in 1918 and more. Lybeck was appointed head of the Military Office of the Ministry for Naval Affairs in 1918 and from 6 June to 13 October 1921, he served as Minister of Defence and head of the Ministry of Defence. During this time, Lybeck was also a member of the Military Pay Experts from 1919 to 1922 and a member of the Defense Audit from 1922 to 1923. He then served as commanding officer of the 4th Coastal Defence Ship Division from 1922 to 1923 and as Inspector of the Submarine Force in 1924. Lybeck was promoted to rear admiral in 1925 and in 1926 he was appointed Highest Commander of the Coastal Fleet. In 1927, he was appointed Chief of the Naval Staff, a position Lybeck had for the next nine years. He was chairman of the Naval Teaching Commission in 1928, and of the board of the Nautical Chart Department from 1929 to 1936. Lybeck was also chairman of the board of the Royal Swedish Yacht Club from 1936 to 1946 and of the Swedish Sailing Federation from 1937. He served as a member of the Committee on Stockholm's Naval Station from 1929 to 1930.
