Tsakiris started playing academy soccer with De Anza Force. In 2015, at the age of 10, he moved to Florida to play with IMG Academy. A couple years later in 2017 he returned to the Bay Area and began play with the San Jose Earthquakes academy for four years, until receiving his first professional contract with San Jose at the beginning of 2022.[2]
Tsakiris made his professional debut with San Jose on March 12, 2022, in an MLS match away to Philadelphia Union. Tsakiris became the third youngest player to appear in MLS for San Jose.[3] Tsakiris made his professional start in San Jose's matchup against Bay Cities FC in the third round of the 2022 U.S. Open Cup. Tsakiris also scored his first professional goal in the 83rd minute of the match.[4]
Niko's father is Shaun Tsakiris, an American former soccer player who is currently an assistant coach of the U.S. under-20 men's soccer team and the director of Los Gatos United academy.[2][7] He is of Greek and Portuguese descent.[8]