Peltonen was born on 29 November 1999 in Nashville, Tennessee. She has two brothers, twins Aleksi and Jesper and a sister, Nelli. Their Finnish parents – Hanna, a former figure skater, and Ville Peltonen, a former ice hockey player – had moved to the United States due to his contract with the NHL's Nashville Predators franchise. The family returned to Finland a few years later. Her paternal grandfather, Esa Peltonen, is also a former professional ice hockey player.
Career
Early years
Peltonen received her first skates when she was two years old, and began learning to skate in 2002. She began competing on the advanced novice level at international events in the 2011–2012 season. She won the novice gold medal at the 2013 Nordic Championships.
Peltonen debuted on the junior international level in the 2013–2014 season. She won the junior silver medal at the Finnish Championships and Nordic Championships, both times finishing second to Jenni Saarinen.
In 2015–2016, Peltonen was coached by Sirkka Kaipio in Helsinki and Järvenpää, and by Rafael Arutyunyan in California. She placed fifteenth at her sole JGP assignment, in Linz, Austria. Making her senior international debut, Peltonen placed tenth at the Finlandia Trophy, a Challenger Series event in October 2015. She did not compete at the Finnish Championships in December but took the junior bronze medal at the Nordic Championships a couple of months later.
2016–2017 season
During the summer, Peltonen trained with Arutyunyan in California. In August, she placed fifth at her JGP assignment in Saint Gervais-les-Bains, France. She then competed at several senior internationals, finishing twelfth at the CS Finlandia Trophy, fourteenth at the Volvo Open Cup, and sixth at the CS Warsaw Cup. In December 2016, Peltonen won the senior gold medal at the Finnish Championships in Tampere, having outscored silver medalist Jenni Saarinen by eight points. She was named in Finland's team to the 2017 European Championships in Ostrava. Ranked fourteenth in the short program and ninth in the free skate, she finished eleventh overall in the Czech Republic. Peltonen competed at the 2017 World Championships in Helsinki, Finland, but did not advance to the free skate, having placed twenty-ninth in the short program.
2017–2018 season
In September 2017, Finland qualified a spot in the ladies' event at the 2018 Winter Olympics, due to Viveca Lindfors' result at the 2017 CS Nebelhorn Trophy. In December, Peltonen won her second consecutive national title, finishing ahead of silver medalist Lindfors by a margin of 4.22 points. In January, Peltonen placed eleventh in the short program, eighth in the free skate, and ninth overall at the 2018 European Championships in Moscow, Russia; she was Finland's top lady at the event, finishing 11 points ahead of Lindfors. On 24 January 2018, the Finnish Olympic Committee selected Peltonen to compete at the Olympics. She finished twentieth in the ladies' event.
2018–2019 season
Peltonen began the new season at the 2018 CS Finlandia Trophy on home soil, finishing in fifth place, two ordinals below Lindfors, who won the bronze medal. She then debuted on the Grand Prix series at the special 2018 Grand Prix of Helsinki, where she placed ninth. Peltonen won the silver medal at the Finnish Championships, finishing behind Lindfors. She finished eighth at the 2019 European Championships, while Lindfors won the bronze medal. Based on the season's results, the Finnish Federation assigned Lindfors to Finland's lone ladies' spot at the 2019 World Championships.
