Portunova broke onto the national stage at the 2013 World Junior Curling Championships, where she threw fourth stones for the Russian team skipped by Alina Kovaleva. After qualifying for the tiebreaker round with a 5–4 round robin record, the Russian team won four sudden-death games en route to capturing the World Junior title.^[3] It was Russia's first title at the event since 2006. They returned to defend their title the following season at the 2014 World Junior Curling Championships but lost in the 3 vs. 4 page playoff game to Sweden's Isabella Wranå. They then defeated Sweden in the bronze medal game to secure third place and bronze medals for the tournament.^[4]

Portunova was the alternate for Team Victoria Moiseeva, who represented Russia at the 2016 European Curling Championships. The team qualified for the event by defeating the two-time world bronze medallist Anna Sidorova rink in the Russian Supercup.^[5] Despite entering the event as rookies, the team qualified for the playoffs with a 6–3 record. They then upset Scotland's Eve Muirhead 11–6 in the semifinal to qualify for the final, where they faced Sweden's Anna Hasselborg. Tied 4–4 in the final end, Hasselborg missed her final draw, giving the Russians two points and the victory.^[6][7] Also during the 2016–17 season, Team Moiseeva won the silver medal at the 2017 Winter Universiade, losing to Canada's Kelsey Rocque in the final.^[8]

The Sidorova rink was initially selected to represent Russia at the 2018 Winter Olympics, but after their poor play during the 2017–18 season, the Russian Curling Federation was forced to hold a best-of-seven Olympic Trials between Team Moiseeva and Team Sidorova to see who would represent the "Olympic Athletes from Russia" team at the Olympics.^[9] Team Moiseeva won the series four games to one, earning them the Olympic spot.^[10][11] At the 2018 Winter Olympics in PyeongChang, South Korea, the team struggled, finishing in a dismal ninth place with a 2–7 record.^[12] Team Moiseeva also represented Russia at the 2018 World Women's Curling Championship where Portunova played third on the team. They had a much stronger tournament at the World's, qualifying for the playoffs with a 7–5 round robin record and defeating the United States to win the bronze medal.^[13]

Portunova joined the Sidorova rink at third for the 2018–19 season. On tour, the team won two events, the Karuizawa International^[14] and the International Bernese Ladies Cup and lost the final of the Stockholm Ladies Cup to Anna Hasselborg. The team also competed in three legs of the 2018–19 Curling World Cup, finishing in third at all three legs they attended. They competed in a best-of-seven series against the Alina Kovaleva rink to represent Russia at the 2019 World Women's Curling Championship but lost the event four games to one.

Team Sidorova started the 2019–20 season at the 2019 Cameron's Brewing Oakville Fall Classic, where they lost in the qualification game.^[15] They next played in the Stu Sells Oakville Tankard where they lost to Anna Hasselborg in the final.^[16] They missed the playoffs at the inaugural WCT Uiseong International Curling Cup^[17] before having a quarterfinal finish at the Women's Masters Basel.^[18] Despite their early successes on tour, Team Sidorova lost the Russian qualifier for the 2019 European Curling Championships to Alina Kovaleva in six games.^[19] They turned things around, however, the following month at the Karuizawa International where they went an undefeated 7–0 throughout the event and defeated Satsuki Fujisawa 5–4 in the final.^[20][21] They also had a semifinal finish at the Glynhill Ladies International and a quarterfinal finish at the International Bernese Ladies Cup. Their final event of the season was at the 2020 Russian Women's World Qualification Event, where they would once again lose to the Kovaleva rink in a best-of-seven series.^[22]

Portunova and her team began the abbreviated 2020–21 season at the 2020 Russian Women's Curling Cup, where they went undefeated until the final, where they lost to Team Kovaleva.^[23] In December 2020, Team Sidorova competed in the 2020 national championship as it had been postponed due to the COVID-19 pandemic. There, they topped the round robin with an 8–1 record, defeating the Kovaleva rink in their final round robin draw. They then lost both the 1 vs. 2 page playoff and final to Kovaleva, settling for silver.^[24] A "curling bubble" was set up in Calgary, Canada in the spring, which hosted several events, including the 2021 World Women's Curling Championship and two slams.^[25] Team Kovaleva qualified for all three events and added Portunova to their lineup due to a conflict with the 2021 Russian Women's Curling Championship where their regular third Maria Komarova was representing the team. At the 2021 Champions Cup, the team qualified for the playoffs before losing to Silvana Tirinzoni in the quarterfinals. They then missed the playoffs at the 2021 Players' Championship, finishing 2–3. The following week, the team represented the RCF (Russian Curling Federation) at the World Championships, as Russia is prohibited from competing under its flag or any national symbols at any Olympic Games or world championships until December 16, 2022. The team finished second through the round robin with an 11–2 record, giving them a direct bye to the semifinals. They then defeated Sweden's Anna Hasselborg 8–7 in the semifinal before losing the final to Switzerland's Silvana Tirinzoni after Kovaleva missed a freeze on her final shot.^[26][27]

In their first event of the 2021–22 season, Team Kovaleva went undefeated to claim the Saint Petersburg Classic.^[28] At the first Slam of the season, the 2021 Masters, the team reached the semifinals where they lost to Tracy Fleury.^[29] They also qualified for the playoffs at the 2021 National, however, lost to Silvana Tirinzoni in the quarterfinal round. At the 2021 European Curling Championships, Team Kovaleva went through the round robin with a 7–2 record, qualifying for the playoffs. They then lost to Sweden's Anna Hasselborg and Germany's Daniela Jentsch in the semifinal and bronze medal games, respectively, placing fourth.^[30] Because of their second place finish at the 2021 World Championship, Portunova and her teammates Alina Kovaleva, Galina Arsenkina, Ekaterina Kuzmina and Maria Komarova qualified directly for the 2022 Winter Olympics where they represented the ROC (Russian Olympic Committee). At the Games, the team had a poor performance, finishing at the bottom of the standings with a 1–8 record.^[31] The Olympics would be the team's final event of the season as due to the Russian invasion of Ukraine, all Russian teams were banned from participating in any World Curling Championships in 2022.^[32] The team was also excluded from the final two Grand Slams of the season, the 2022 Players' Championship and the 2022 Champions Cup. At the end of the season, Team Kovaleva competed in the 2022 Nornickel Curling Cup, held only between Russian teams. There, they finished in third place.^[33]

Portunova is a full-time curler.^[1]

• Yulia Portunova at World Curling 
• Yulia Portunova at Olympics.com 
• Yulia Portunova at Olympedia