Jaka Blažič started his professional sports career in 2007 in the jersey of Triglav from Carniola, and after two years of playing for the Gorenjska team, he went to Ljubljana for the first time and wore the jersey of Slovan in 2009. He also stayed at Kodeljevo for two years, and then in 2011 he transferred to the then Union Olimpija. The path then led him to Crvena Zvezda Belgrade, Baskonia, Andorra and Barcelona, and before the start of the 2019/20 season, he returned to Cedevita Olimpija and played in 21 matches, in 28.5 minutes, in the regional competition in the 2019/20 competitive season. which he beat on the court, averaging 15.1 points, 5.6 rebounds and 2.7 assists per game. In the 7DAYS EuroCup, captain Zmajev averaged 9.8 points, 4.0 rebounds and 2.4 assists per game in 27.5 minutes. He was named the round’s most valuable player of the regular season of the ABA League three times, and with this achievement he became the only basketball player who performed on the regional scene in the prematurely ended 2019/20 season.

In the 2020/21 season, Blažič was selected as the most valuable player of the month in the regional league in November. In the end, Jaka was also selected in the First Team of the regional competition for the 2020/21 season, and at the same time he was part of the Second Team of the 7DAYS EuroCup competition. Blažič also concluded the European Cup as the top scorer in the 2020/21 competitive season, with an average of 19.1 points per game.

In the 2021/22 season, the last one that Blažič spent at Cedevita Olimpija, he scored 15.4 points, 4.8 rebounds and 3.6 assists per game in the 7DAYS EuroCup, and recorded 14.1 points in the regional league. 4.9 rebounds and 2.5 rebounds per faceoff. Blažič was selected in the second five in the European Cup, and in the regional league he was selected in the Ideal Five for the second season in a row.

After the end of the 2021/22 season, Blažič moved to the Turkish team Bahçeşehir Koleji, where he played in 11 games of the Champions League this season, averaging 5.5 points and 1.9 rebounds per game. In the Turkish national championship, he scored 5.2 points, 2.2 rebounds and 1.0 assists, and played in 13 games.

Jaka is also a permanent member of the Slovenian men’s national team, with which he won the title of European champion in 2017, and in 2021 he won fourth place at the Olympic Games in Tokyo. In the qualifiers for this World Cup 2023, he played in seven games and averaged 10.1 points, 4.3 rebounds and 1.7 assists, and at EuroBasket 2022 he also appeared in seven games, scoring 8.1 points, 2.0 rebounds and 1.0 assists.