Mariani made her international debut at a 2010 friendly meet between junior gymnasts from Italy, France, Germany, and Switzerland.

The Italian team of Mariani, Serena Bugani, Elisa Meneghini, Lara Mori, and Martina Rizzelli won the gold medal.

[4] Mariani competed at the 2012 City of Jesolo Trophy and helped the Italian junior team finish second behind the United States.

[5] She was then selected to compete at the 2012 Junior European Championships alongside Elisa Meneghini, Lara Mori, Tea Ugrin, and Alessia Leolini, and they won the silver medal behind the Russian team.

[20] She was then selected to compete at the World Championships alongside Carlotta Ferlito, Erika Fasana, Elisa Meneghini, Lara Mori, and Tea Ugrin.

[25] At the City of Jesolo Trophy, she won a bronze medal with the Italian team and also placed eleventh in the all-around, sixth on balance beam, and fifth on floor.

[26] She competed at the European Championships alongside Elisa Meneghini, Lara Mori, Martina Rizzelli, and Sofia Busato, and they finished fifth in the team final.