Smits started her youth career with
OJC Rosmalen at the age of six. She spent eight years there playing alongside boys before moving to Brabant United. In 2015, she moved to CTO Eindhoven. In May 2017, Smits signed her first professional contract with
Eredivisie club
Twente. She made her debut on 1 September in a 3–0 league win against
Zwolle. She scored in 58th minute of the game before being replaced by Bente Jansen. She scored 25 goals in 21 league matches during the
2018–19 season to help her club win the league title. In February 2019, it was confirmed that Smits would join
PSV prior to the
2019–20 season. She was top Eredivisie scorer when football leagues across Netherlands were suspended by Dutch government in March 2020 due to the
COVID-19 pandemic. On 15 September 2020, German
Frauen-Bundesliga club
VfL Wolfsburg announced that Smits has signed a three-year contract with the club, which would start in July 2021. On 5 June 2021, she played her last match for PSV in the cup final against
ADO Den Haag. She scored the only goal in the match to win PSV's first trophy in its history. With 52 goals from 45 matches across all competitions, Smits left the club as PSV's all-time top scorer. During her only season with Wolfsburg, Smits won the German league and
domestic cup titles. On 3 June 2022, her contract with the club was terminated by mutual agreement. She returned to her former club PSV on the same day, signing a three-year contract until June 2025. On 30 June 2025, Smits joined
Ajax on a two-year contract until June 2027. ==International career==