Sedov was born in the village of Krivaya Kosa of Taganrog district (now Novoazovskyi Raion, Donetsk Oblast) to a fisherman's family.
On August 14 (27), 1912, Sedov's ship Svyatoy Muchenik Foka (Saint Phocas the Martyr) left Arkhangelsk and had to stay for the winter near Novaya Zemlya because of impassable ice.
The expedition reached Franz Josef Land only in August 1913; however, it had to stay for the second winter in the Tikhaya Bay due to lack of coal.
On February 2 (15), 1914, Sedov (already sick with scurvy) and his accompanying seamen G. Linnik and A. Pustotniy set off for the North Pole with their draft dogs.
On the way back, at Franz Josef Land, the Svyatoy Foka rescued two survivors of the Brusilov expedition, including Valerian Albanov.