Oleg Valerianovich Basilashvili was born on September 26, 1934, in Moscow, USSR. His father, named Valerian Basilashvili, was a director of the Moscow Polytechnical College. His mother, named Irina Ilyinskaya, was a teacher of linguistics.

His father made up a story that his grandfather was a Colonel in the Imperial Army of the Tsar Nicholas II, then married a Polish lady, and settled down, becoming a policeman. He also fabricated a story that grandfather once arrested a dangerous criminal, named Dzhugashvili, who was really Joseph Stalin. In reality Basilashvili's maternal grandfather was a Russian orthodox priest and an architect, who participated in the construction of the Cathedral of Christ the Saviour in Moscow. During the Second World War young Oleg Basilashvili was evacuated from Moscow to the Transcaucasian republic of Georgia. There went to a primary school and lived with his paternal grandfather until the end of WWII.

In 1956 Oleg Basilashvili graduated from the Acting School of the Moscow Art Theatre. He made his film debut as a young groom in 'Nevesta' (The Bride, 1956) by director Grigori Nikulin, based on a story by Anton Chekhov. At that time together with his first wife, Tatyana Doronina, Basilashvili joined the troupe at the Bolshoi Drama Theatre (BDT) in St. Petersburg (then Leningrad) under the leadership of the legendary director Georgi Tovstonogov. Since 1959 Basilashvili has been a permanent member of the troupe at the BDT in St. Petersburg. There his stage partners were such stars as Kirill Lavrov, Tatyana Doronina, Alisa Freyndlikh, Lyudmila Makarova, Svetlana Kryuchkova, Zinaida Sharko, Valentina Kovel, Innokentiy Smoktunovskiy, Sergey Yurskiy, and many other remarkable Russian actors. Basilashvili's most memorable stage works were in 'Gore ot Uma' by the playwright Aleksandr Griboyedov, 'Uncle Vanya', a play by Anton Chekhov, 'Kholstomer', based on story by Leo Tolstoy, 'Na Dne', a play by Maxim Gorky, and other classic plays, directed by Georgi Tovstonogov at the BDT in St. Petersburg.

Oleg Basilashvili has been one of the favorite actors of film director Eldar Ryazanov. They collaborated in such popular films as Sluzhebny Roman (1977), Vokzal Dlya Dvoikh (1982), Nebesa obetovannye (1991), and Predskazanie (1993), which became significant box-office hits. His film partners were Alisa Freyndlikh, Lyudmila Gurchenko, Nikita Mikhalkov, Nonna Mordyukova, Evgeniy Leonov, Natalya Gundareva, and many other Russian film actors.

One of his most famous film works was made in collaboration with director Georgiy Daneliya in a remarkable film Osenniy marafon (1979). The film is a cross-genre comedy and melodrama with a bitter humor and satire of the Soviet life. In it Basilashvili plays a man in his mid-life crisis, who is torn between two nice women, his wife and his mistress, and all three of them become entangled in the game of lies and personal demands, being at the same time strangled by the stagnant Soviet reality. Basilashvili co-created a memorable acting ensemble with such actors, as Natalya Gundareva, Evgeniy Leonov, Marina Neyolova, and Nikolay Kryuchkov. The film became a Soviet classic, and director Georgiy Daneliya was awarded at International film festivals in Berlin and San Sebastian.

Oleg Basilashvili made a comeback with an impressive performance in the role of Woland in Master i Margarita (2005), an adaptation of the eponymous novel of Mikhail A. Bulgakov by director Vladimir Bortko. In his own words, Basilashvili played the character of Woland in resemblance of an authoritarian and manipulative bureaucrat, alluding to a Soviet-era dictator. Basilashvili created a powerful interplay with a stellar ensemble of actors, such as Aleksandr Abdulov, Kirill Lavrov, Anna Kovalchuk, Aleksandr Galibin, and other notable Russian actors.

Oleg Basilashvili received the title of People's Artist of the USSR. He was awarded the State Prize of the Soviet Union and was decorated by the Russian government. Basilashvili was elected the representative of Leningrad (St. Petersburg) in 1990. He was a supporter of president Boris Yeltsin and a member of the parliamentary group of democratic representatives. Oleg Basilashvili was a proponent of returning the original name to the city of St. Petersburg. He quit politics after 2000, and focused on his acting career.

Basilashvili is currently residing in St. Petersburg, Russia, with his second wife, Galina Mshanskaya, who is a popular TV show hostess.