Janković was born March 3, 1990, in Belgrade, SR Serbia, SFR Yugoslavia. He is the son of the famous late Serbian professional basketball player Boban Janković, who was tragically paralyzed during a Greek Basket League playoff game between Panionios and Panathinaikos in 1993.
Janković moved to Greece with his family at the age of two, when his father, Boban, joined the Greek club Panionios for the 1992–93 season.
Janković began his professional career with the Greek Basket League club Panionios in 2007. In 2008, he moved to Mega, on loan from Panionios. He then returned to Panionios in 2009.
On 20 June 2013, Janković joined the Greek club Panathinaikos. He was announced as a new player of Panathinaikos, for the following three years, along with his Panionios teammate Nikos Pappas. During his second season at the club, he switched his jersey number from 16 to 8.
Janković played in the 2016 NBA Summer League, with the Summer League squad of the New Orleans Pelicans.
On August 3, 2016, Janković signed with the Spanish Liga ACB club Valencia. On October 31, 2016, he was loaned to the Greek club Aris Thessaloniki, for the rest of the season.
On July 20, 2017, Janković signed with Andorra.
Janković won the gold medal at the 2008 FIBA Europe Under-18 Championship, while playing with the junior Greek national basketball team. Janković also won the silver medal at the 2009 FIBA Under-19 World Cup and the gold medal at the 2009 FIBA Europe Under-20 Championship. He also won the silver medal at the 2010 FIBA Europe Under-20 Championship with Greece's junior national team.
He became a member of the senior men's Greek national basketball team in 2013, when he was invited to train with the team during its preparation phase before the EuroBasket 2013.
Janković speaks Greek, Serbian, and English fluently. In Greece, he is known by the name of Vladimiros "Vlanto" Giankovits (Βλαδίμηρος "Βλάντο" Γιάνκοβιτς).
Note: The EuroLeague is not the only competition in which the player participated for the team during the season. He also played in domestic competition, and regional competition if applicable.Greek League All-Star: (2013)
Greek League Most Improved Player: (2013)
Greek League Best Five: (2013)
3x Greek Cup Winner: (2014, 2015, 2016)
Greek League Champion: (2014)
2008 Albert Schweitzer Tournament: Gold
2008 FIBA Europe Under-18 Championship: Gold
2009 FIBA Under-19 World Cup: Silver
2009 FIBA Europe Under-20 Championship: Gold
2010 FIBA Europe Under-20 Championship: Silver