Gagarina was born in Moscow, Russian SFSR, USSR but spent most of her youth in Greece. Her mother was a ballet dancer. In 1993, Gagarina's father died and her mother decided to move the family back to Russia. However, they soon moved back to Greece and settled in Athens. After completing her education, she moved to Saratov to live with her grandmother.
In 2003, Gagarina competed in season two of Star Factory, a Russian reality singing competition. She performed several songs by Maxim Fadeev and went on to win the show, but refused to work with Fadeev after her victory.
After winning Star Factory, Gagarina was invited to perform in the group Playgirls. The group received a recording contract with ARS Records, but ultimately disbanded. In 2005, she performed at the New Wave competition held in Jūrmala, Latvia and placed third. She later released the singles "Kolybelnaya", "Morning", "Ya tvoya", "Pomnyu", and "Ya tebya ne proshchu nikogda". Her début album Poprosi u oblakov was released in 2007.
In 2008, Gagarina released the single "Komu, zachem?" with Russian singer Irina Dubtsova. In March 2010, her second studio album O sebe was released.
In 2012, Gagarina starts to collaborate with Konstantin Meladze, Russian/Ukrainian producer, well-known for his successful project "VIA GRA". With Meladze she recorded four singles " Spektakl okonchen " ("Show Is Over") RUS #10, UKR #5, "Net" ( "No") RUS #3 UKR #1, "Navek" ( "Ever") RUS #25, UKR #23, "Shagay" ( " Walk Away") RUS #21, UKR #25.
On 9 March 2015, it was revealed that Gagarina would represent Russia in the Eurovision Song Contest 2015.