In 1905, he married his paternal first cousin, Princess Victoria Melita of Saxe-Coburg and Gotha, defying Nicholas II by not obtaining his consent.

During the February Revolution of 1917, Kirill marched to the Tauride Palace at the head of the Naval Guards and swore allegiance to the Russian Provisional Government.

He worked for the restoration of the monarchy from exile for the rest of his life, but his claims were contested by some factions of the monarchists in a division that continues today.

[6] He received military training and religion instruction, and learned the languages spoken by the Romanovs: Russian, English, French and German.

[8] From an early age, Grand Duke Kirill had a love for the sea and his parents encouraged him to follow a career in the Imperial Navy.

During the coronation festivities in Moscow, Kirill fell in love with his paternal first cousin, Princess Victoria Melita of Saxe-Coburg and Gotha.

They flirted with each other at the balls and celebrations, but Victoria Melita was already married to Ernest Louis, Grand Duke of Hesse, the only brother of Tsarina Alexandra.

With the start of the Russo-Japanese War, he was assigned to serve as First Officer on the battleship Petropavlovsk, but the ship was blown up by a Japanese mine at Port Arthur in April 1904.

Grand Duke Kirill married his first cousin, Princess Victoria Melita of Saxe-Coburg and Gotha on 8 October 1905 without any consent from Tsar Nicholas II.

Victoria's mother was Grand Duchess Maria Alexandrovna of Russia, a daughter of Tsar Alexander II and Kirill's paternal aunt.

The marriage caused a scandal in the courts of European royalty as Princess Victoria was divorced from her first husband, Grand Duke Ernst Ludwig of Hesse, also her first cousin.

This elevation was openly denounced by Grand Duke Nicholas Nikolaevich when he published a private letter of the Dowager Empress in 1924 in which she stated that Kirill's assumption of the position was "premature."

"[18] During the February Revolution of 1917, Kirill marched to the Tauride Palace at the head of the Garde Equipage (Marine Guard) to swear allegiance to the Russian Provisional Government, wearing a red band on his uniform.

[13][19] Kirill had authorised the flying of a red flag over his palace on Glinka Street in Petrograd and in correspondence with a Romanov relative claimed credit for "saving the situation by my recognition of the Provisional Government".

[13] While living in exile, he was supported by some émigrés who styled themselves "legitimists" (legitimisti, in Russian легитимисты), underlining the "legitimacy" of Kirill's succession.

The opponents of Kirill were known as the "un-predetermined" (nepredreshentsi, in Russian непредрешенцы); they believed that in the wake of the radical revolutionary events that the convening of a Zemsky Sobor was necessary in order to choose a new monarch for Russia.

Kirill found his strongest support among a group of legitimists known as the Mladorossi, a Russian émigré monarchist organization that ultimately became heavily influenced by fascism – although it distanced itself from other fascist movements.

[25]: 47  Following the Dissolution of the Soviet Union, the remains of Kirill and his spouse were transferred from Coburg to the Grand Ducal Mausoleum of the Peter and Paul Fortress in St. Petersburg, Russia on 7 March 1995 after negotiations conducted by his granddaughter Maria Vladimirovna.