She found opportunities for field soccer limited in her native Baixada Santista, especially after Santos FC's women's section was closed in 2012.

[3] She subsequently received an offer from FC Girondins de Bordeaux and joined the French Division 1 Féminine club halfway through their 2017–18 season.

[5] After a successful 2019 FIFA Women's World Cup with Brazil, and an elite level performance against France, Kathellen was linked to many major European clubs, including newly promoted CD Tacón, due to become Real Madrid for season 2020–21.

[7] In 2024 she left Real Madrid and joined Al-Nassr on a two years contract, her official debut was on the 25 of August in the AFC Women's Champions League which she helped her team to keep a clean sheet at.

[11] Despite being the youngest Brazilian player in the lineup for the Round of 16 game thriller against France, Kathellen delivered a major performance.