Early career

O'Shea began learning to skate in 1995.^[2] He competed with Christine Mozer in the 2011–2012 season, Caroline Knoop in 2010–2011, and Jessica Calalang in 2009–2010. He also competed in singles until 2011.

O'Shea teamed up with Tarah Kayne in April 2012.^[3]

2012–2013 season

Kayne/O'Shea finished seventh in their first trip to the U.S. Championships in January 2013. Making their international debut, they won the silver medal at the 2013 International Challenge Cup.^[4]

2013–2014 season

Kayne/O'Shea won bronze medals at the U.S. Classic and Ice Challenge. After placing sixth at the 2014 U.S. Championships, they were assigned to the 2014 Four Continents, where they won the silver medal.

2014–2015 season

On July 28, 2014,^[5] Kayne underwent surgery due to a labral tear in her right hip.^[6] As a result, the pair withdrew from their 2014–15 Grand Prix assignments, the 2014 Cup of China and 2014 Rostelecom Cup.^[7] Kayne/O'Shea returned to competition at the 2014 Golden Spin of Zagreb, taking bronze at the ISU Challenger Series (CS) event. The pair stepped onto their first national podium at the 2015 U.S. Championships, where they were awarded the bronze medal.

2015–2016 season

Kayne/O'Shea began their season with gold at a CS event, the 2015 U.S. International Classic. Kayne injured her right knee at the event.^[8]

Making their Grand Prix debut, the pair placed sixth at the 2015 Skate America and fourth at the 2015 Rostelecom Cup. Another Challenger medal followed, bronze at the 2015 Golden Spin of Zagreb in December.^[9] In January, Kayne/O'Shea placed first^[10] in both segments at the 2016 U.S. Championships and won the gold medal by a margin of 14.85 points over defending champions Alexa Scimeca / Chris Knierim.^[11]

2016–2017 season

After placing fifth at the 2016 CS Finlandia Trophy, Kayne/O'Shea competed at two Grand Prix events, finishing sixth at the 2016 Skate America and fourth at the 2016 NHK Trophy. The pair withdrew from the 2017 U.S. Championships due to a concussion, Kayne having hit her head while attempting a throw triple flip during the short program on January 19.^[12]

During the season, Kayne experienced increasing pain due to right knee tendinitis,^[12] the result of her 2015 injury.^[8] She received a new cadaver tendon in an operation at the Vail Valley Medical Center on February 14, 2017, and then refrained from walking for seven weeks.^[8] She resumed training in July 2017.^[8]

2017–2018 season

Kayne/O'Shea did not compete in the early part of the season, including the Grand Prix, instead beginning the season at the 2017 CS Golden Spin of Zagreb, where they won the bronze medal. They took silver at the 2018 U.S. Championships and were named first alternates for the 2018 Winter Olympics, where the United States had only one pairs spot, as well as part of America's teams for the Four Continents and World Championships.^[13]

At the 2018 Four Continents Championships, they were third after the short program and then had a personal best score in the free skate to win the gold medal, the first American team to do so in over a decade.^[14] Kayne said she felt "really great about our performance," They anticipated competing at the World Championships.^[13] However, following the event, Kayne was diagnosed with a stress fracture in her right knee.^[15] As a result, they withdrew from the World Championships, and were replaced by bronze medalists Deanna Stellato / Nathan Bartholomay.^[16]

They were coached by Jim Peterson, in Ellenton, Florida, until the end of the season.^[17]

2018–2019 season

On September 7, 2018, Kayne/O'Shea announced a coaching change, deciding to join Dalilah Sappenfield in Colorado Springs, Colorado.^[18] They began the season with a seventh-place finish at the 2018 CS Nebelhorn Trophy. Assigned to two Grand Prix events, they first competed at the 2018 NHK Trophy, finishing fifth. At the 2018 Internationaux de France, Kayne/O'Shea were fourth after the short program but placed second in the free skate, finishing less than two points ahead of bronze medalists Aleksandra Boikova / Dmitrii Kozlovskii. This was their first Grand Prix medal. Kayne remarked that after a "less than desirable" performance in Japan, "to have come to France and make this much improvement in just two short weeks made us both very happy."^[19]

At the 2019 U.S. Championships, Kayne/O'Shea placed first in the short program, just ahead of Ashley Cain / Timothy LeDuc. In the free skate, they made some small opening mistakes on their twist and side-by-side jumps but then had a major error when they failed to execute their final lift, which caused them to drop to fourth place. O'Shea commented afterward, "I didn’t do what I was supposed to do." They were nevertheless named to the American team for the Four Continents Championships over bronze medalists Stellato-Dudek/Bartholomay.^[20] They finished in sixth place there, with Kayne saying their performance was a personal disappointment.^[21]

2019–2020 season

Kayne/O'Shea began with a fourth-place finish at the 2019 CS U.S. Classic. On the Grand Prix, they were sixth to begin at the 2019 Cup of China.^[22] Kayne/O'Shea were sixth as well at the 2019 NHK Trophy.^[23]

Competing at the 2020 U.S. Championships, Kayne/O'Shea placed second in the short program, seven points behind the leaders, Knierim/Knierim.^[24] Third in the free skate, they won the bronze medal behind the Knierims and Calalang/Johnson. O'Shea called it "an improvement as the program has progressed over the first part of the season. We are taking steps in the right direction."^[25] They finished the season with a fifth-place finish at the 2020 Four Continents Championships.^[26]

2020–2021 season

In September, Kayne and O'Shea announced they were leaving coach Dalilah Sappenfield, at the time saying publicly that they were looking forward to exploring new training options and looking forward to staying strong as a team.^[27]

They were fourth at the ISP Points Challenge, a virtual domestic competition. They competed at the 2020 Skate America, primarily attended by American pairs teams due to travel restrictions relating to the COVID-19 pandemic.^[28] Their previous coaches Jim Peterson and Amanda Evora helped them to prepare for the competition. The permanent training environment of Kayne and O'Shea will be determined after the competition.^[29]

On December 10, it was announced that Kayne and O'Shea had split, with Kayne subsequently retiring.^[30][31]

2021–2022 season

At the end of June, USFSA added O'Shea to the International Selection Pool, which is a list of teams eligible for international competition, with new partner, Chelsea Liu.^[32] Liu/O'Shea finished fifth in their international debut at the Cranberry Cup, and went on to make their Grand Prix debut together at the 2021 Skate America, where they came seventh.^[33] However, their partnership was derailed by an on-ice accident at the 2021 CS Warsaw Cup that left both concussed. They withdrew from the 2022 U.S. Championships, and ultimately their partnership ended.^[34][35]

2022–2023 season

Initially uncertain how to proceed following the end of his partnership with Liu, O'Shea spent some time offering coaching assistance to other pairs skaters, before eventually forming a new partnership with Ellie Kam.^[35] In the fall, they made their international debut at the 2022 Ice Challenge and won the gold medal in the pairs competition. They then made their Challenger debut at the 2022 CS Golden Spin of Zagreb, winning the silver medal.^[36]

Kam/O'Shea competed next at the 2023 U.S. Championships, where they placed third in the short program.^[37] They opened their free skate with Kam falling on their triple twist, but still managed to place third in that segment as well, winning the bronze medal. Kam called the experience "quite the whirlwind."^[38]

Having reached the national podium, Kam/O'Shea were assigned to make their ISU championship debut together at the 2023 Four Continents Championships, held in their home training location of Colorado Springs. O'Shea considered this "pretty special."^[39] They placed seventh in the short program, but a fifth-place free skate moved them up to sixth overall.^[40][41] Kam/O'Shea finished the season at the 2023 World Championships in Saitama, where they finished twelfth.^[42]

2023–2024 season

Kam/O'Shea began the season with a victory at the 2023 CS Finlandia Trophy.^[43] They were invited to make their Grand Prix debut at the 2023 Grand Prix de France, and finished fifth in the short program, but had to withdraw after Kam suffered an injury in training.^[44] Despite this, Kam/O'Shea were able to attend their second Grand Prix, the 2023 Grand Prix of Espoo, coming sixth.^[45]

At the 2024 U.S. Championships, Kam/O'Shea finished second in the short program with a score of 64.57, with Kam having struggled on the throw landing and O'Shea two-footing his jump. Segment leaders Chan/Howe withdrew in advance of the free skate, leaving Kam/O'Shea the de facto first-place finishers heading into that segment. They were second in the free skate behind Efimova/Mitrofanov, but won their first national title by 0.85 points. O'Shea enthused that "being first is amazing," while noting there was room to improve on their performance, in particular continued difficulties with throw landings.^[46]

Kam/O'Shea had already been named to the American team for the 2024 Four Continents Championships in advance of the national championships, due to the events being separated by less than a week.^[47] Traveling to Shanghai for the competition, they finished fourth in the short program despite Kam's throw fall, before a second-place free skate lifted them to the bronze medal, their first international championship podium as a team. Kam noted that the turnaround between the events was such that she did not feel their national gold had "sank in yet."^[48]

In the short program at the 2024 World Championships in Montreal, Kam fell on their throw triple loop, but the team was otherwise clean and they came tenth in the segment. O'Shea said that it was "nice to see that with a fall – a fairly large mistake – we still get a season-best. That means the other things we’ve been working on are improving and the judges are starting to see that piece as well."^[49] Difficulties with jumps and throws continued in the free skate, and Kam/O'Shea dropped to eleventh overall.^[50]

With Kam

With Liu

With Kayne

With Kam

With Liu

With Kayne

Single skating

With Kam

With Liu

With Kayne

Current personal best scores are highlighted in bold.

Small medals for short and free programs awarded only at ISU Championships.