[3] His figure skating role models include Stéphane Lambiel, Daisuke Takahashi, Patrick Chan, and Javier Fernández.

[11] Vasiļjevs debuted on the ISU Junior Grand Prix circuit in 2013, placing 7th in Riga, Latvia and 10th in Gdańsk, Poland.

[13] During the 2014–15 figure skating season, Vasiļjevs placed fourth at both of his Junior Grand Prix assignments, in Courchevel, France and Tallinn, Estonia.

He won the silver medal at the European Youth Olympic Winter Festival, held in January 2015 in Dornbirn, Austria.

[16][17] Making his senior international debut, he placed 5th at the 2015 Mordovian Ornament before taking the bronze medal at the 2015 Tallinn Trophy.

Ranked third in the short program and first in the free skate, he finished second overall with a total score 1.09 less than gold medalist Sōta Yamamoto of Japan.

[11] In March, at the 2016 World Junior Championships in Debrecen, Hungary, he won a small bronze medal for the short program and finished 8th overall.

Due to his result, Latvia qualified a spot in the men's event at the 2018 Winter Olympics in Pyeongchang, South Korea.

[34] In December, Vasiļjevs won his third national title,[35] and along with Diāna Ņikitina, was subsequently selected to represent Latvia in figure skating at the 2018 Winter Olympics.

[46] In October, Vasiljevs competed at Japan Open, placing fifth in his segment but winning silver as part of team Europe.

He began on the Grand Prix at the 2019 Skate Canada International, placing fourth in the short program after putting a foot down on his triple Lutz.

[54] Only fifth in the short program, he won the free skate and the gold medal, in the process landing a quad Salchow for the first time.

[59] His first Grand Prix event was scheduled to be the 2021 Cup of China, but following its cancellation, he was reassigned to the 2021 Gran Premio d'Italia in Turin.

[60] He was fourth at that event as well with new person bests in the free skate and total score, and praised the "overwhelming feeling" of competing for an audience again.

Seventh in the free skate after errors on both his quad Salchow attempt and one of his triple Axels, he again finished fourth overall while still setting new personal bests again.

"[63] Named to his second Latvian team for the 2022 Winter Olympics, Vasiljevs placed sixteenth in the short program of the men's event.

"[66] He won the bronze medal at the 2022 CS Nepela Memorial to start the season before finishing tenth at the 2022 Skate Canada International.

[59] Vasiljevs rallied from this disappointing result and won the silver medal at his second Grand Prix, the 2022 MK John Wilson Trophy.

"[67] Seeking to defend his podium place at the 2023 European Championships, Vasiljevs finished third in the short program despite underrotating part of his jump combination, winning a small bronze medal.

[59] After feeling somewhat disappointed by his results in the prior season, Vasiljevs set a goal to focus on the upcoming European Championships.

[73] He went on to finish seventh at the 2023 NHK Trophy, and said he was continuing to struggle with the balance between technical development and "keeping my passion for artistry.