Earlier in her career, Gilles competed for the United States with Timothy McKernan and Zachary Donohue, winning four medals altogether on the ISU Junior Grand Prix series.

[5] The Gilles family household in Colorado routinely played host to other skaters training in the area during her childhood, including Adam Rippon, Liam Firus and Yukina Ota.

She appeared in the band Simple Plan's music video for the song "Can't Keep My Hands off You", and was offered the role of Rapunzel in Disney on Ice's production of Tangled.

They finished as second alternates for the Grand Prix Final after taking bronze at the 2015 Skate America and silver at the 2015 Trophée Éric Bompard.

[27] They finished fifth at the 2016 Four Continents Championships, a result they considered disappointing, and which prompted significant revisions to their short dance program, which had initially been developed as a mix of music by The Beatles and Wolfgang Amadeus Mozart.

At the 2016 World Championships in Boston, Gilles/Poirier debuted the new program iteration, finishing fifth in the short and making the final flight in the free dance for the first time in their partnership.

[29] The 2016–17 season featured the return to competition of Tessa Virtue / Scott Moir, which affected the standings of the other Canadian ice dance teams.

The two struggled with mistakes in their disco-themed short dance for much of the season, with a stumble at the French event and Gilles falling at the 2017 Four Continents Championships.

"[31] Their scores dramatically improved with the new program, and they earned the silver medal at the 2018 Canadian championships on the way to qualifying for the 2018 Winter Olympics in Pyeongchang, South Korea.

[34] At their first Grand Prix event, the 2018 Skate Canada International, Gilles fell during the rhythm dance, leaving them in sixth place.

[57] With the pandemic continuing to make in-person competitions difficult, Gilles/Poirier competed at a virtually-held 2021 Skate Canada Challenge, winning the gold medal by a margin of 16.42 points over silver medalists Fournier Beaudry/Sørensen.

[58][59] On February 25, Gilles and Poirier were announced as part of the Canadian team to the 2021 World Championships, to be held in Stockholm without an audience due to the pandemic.

[60] Four-time and defending World champions Papadakis/Cizeron had declined to attend the event due to the pandemic and their own past COVID illness, resulting in the podium being considered more open than in previous seasons, with Gilles/Poirier among the six teams viewed as contenders.

They came second in the free dance with a new personal test in both that segment and in total score, rising to third overall and finishing only 0.36 points behind the silver medals, Madison Hubbell and Gilles' former partner Zachary Donohue.

[63] In the aftermath of their World medal win, Gilles and Poirier could not tour with ice shows due to ongoing pandemic restrictions and so focused on their preparations for the Olympic season.

"[64] Making their season's debut at the 2021 CS Autumn Classic International, they won the event for the second time in the first major skating competition held in Canada in a year and a half.

[67] Assessing the results, Gilles said that she felt they had "made some improvements compared to Skate Canada, but our score is a bit lower, and we need to go back and evaluate that.

[69] At the 2022 Canadian Championships, held in Ottawa without an audience due to the pandemic, Gilles/Poirier easily won both segments of the competition to take their second national title.

Theirs was the highest placement for Canada on the first day of competition, which was notably missing Canadian men's champion Keegan Messing due to COVID-19 rules.

[79][80] Poirier said that "I don't think the results in the second half of the season were exactly how we wanted them to be, but I think, especially after the free dance skate at the Olympics, we were so proud of our performance today, and we had a blast.

They received lower levels on some elements than in previous events, which Poirier called "a fair assessment" that he attributed to hesitance in the face of strong competition.

"[91] Their training mates, Nadiia Bashynska and Peter Beaumont, won gold in the Junior Grand Prix Final on the same day.

[13] Able to return to competition for the 2023 World Championships in Saitama, Gilles/Poirier finished in third place in the rhythm dance, less than a point behind second-place Guignard/Fabbri but solidly behind segment leaders Chock/Bates.

[97] After going public with her cancer surgery a month later, Gilles called the Saitama championships "one of the hardest competitions I've ever had to do in my life, just because I had to face people again, they wanted to know how I was doing, and I had lovely messages online.

"[101] Beginning the Grand Prix at the 2023 Skate Canada International, they won the gold medal with a score only 0.48 higher than their personal best, nearly ten points clear of repeat silver medalists Fear/Gibson.

[102] They next appeared at the Cup of China for the first time in their careers, entering as the favourites, but encountered difficulties in the rhythm after Gilles had a twizzle error.

Gilles explained afterward that "our big focus of the program was to try to amplify the energy and performance," opining that "I felt I gave too much, and so I wasn't really grounded.

[104] Returning to China for the 2023–24 Grand Prix Final, this time in Beijing, Gilles/Poirier came third in the rhythm dance, narrowly behind Guignard/Fabbri in second place but nearly nine points clear of Fear/Gibson in fourth due to errors by the latter.

"[111] For the free dance, they chose to adapt one of their show programs from the summer's Stars on Ice tour, using Annie Lennox's cover of "A Whiter Shade of Pale".

[113] Poirier made another significant error at the Final, falling in the pattern step element, as a result of which they placed a distant sixth among the six teams competing in the segment.